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• o' 




HIGH FREQUENCY 
APPARATUS 

DESIGN, CONSTRUCTION AND PRACTICAL 
APPLICATION 



A PEACTICAL TREATISE 
FOR ELECTRICAL ENGINEERS, ELECTRICIANS, 
PHYSICIANS, STUDENTS AND EXPERIMENTERS. 
COVERS THE DESIGN AND CONSTRUCTION OF 
ALL KINDS OF HIGH FREQUENCY APPARATUS 
FOR USE IN EXPERIMENTAL, MEDICAL AND 
PLANT CULTIVATION WORK. 

Includes Also 

Directions for the Construction of a Complete Stage Outfit for 

Both Low and High Potential Work. 



BY 

THOMAS STANLEY CURTIS 

AUTHOR OF 

"Experimental High Frequency Apparatus," ■'Construction of In- 

Ition Coils and Transformers," -Model Submarine With Wire- 
less Control," Etc. 



WCOND EDITION, REVISED AND ENLARGED 



I 



NEW YORK 

ORMAN W. HENLEY PUBLISHING COMPANY 
2 WEST 45th street 
1920 



< 



Copyrighted 1920 
BY THE NORMAN W. HENLEY PUBLISHING CO. 

Copyrighted 1916 
BY THO^LVS STANLEY CURTIS 
All Rights Reserved 



Printed in U. S. A. 



SEP 22 19. . 
©CI,A597487 



PREFACE 

This volume has been prepared in response to a general 
demand created by a series of articles which appeared in 
Electrician and Mechanic, Popular Electricity and Modern 
Mechanics, and 7 he World's Advance. The articles covered 
briefly the apparatus employed in an experimental study of 
high frequency current phenomena over a period of several 
years. 

In this w^ork, I have spared no efifort to produce a treatise 
of practical value. Theory has been ignored chiefly because 
'it would serve merely to confuse the non-technical reader. 
.The designs offered are more than theoretical — they are the 
result of actual construction and experiment. In many cases, 
the entire oscillation transformer has been rebuilt and rewound 
many times before satisfactory results were obtained. 

The work has been divided into six basic parts. The first 
^two chapters tell the uninitiated reader what the high fre- 
quency current is, what it is used for, and how it is produced. 
The second section comprising four chapters describes in de- 
tail the principles of the transformer, condenser, spark gap, 
and oscillation transformer, and covers the main points in the 
design and construction of these devices as applied to the work 
in hand. The third section covers the construction of small 
ihigh frequency outfits designed for experimental work in 
the home laboratory or in the class room. The fourth sec- 
tion is devoted to electro-therapeutic and X-Ray apparatus. 
The fifth describes apparatus for the cultivation of plants and 
Ivegetables. The sixth section is devoted to a comprehensive 
discussion of apparatus of large size for use upon the stage 
in spectacular productions. 
i 3 



4 PREFACE 

I wish to acknowledge my indebtedness to the following 
concerns and individuals for assistance rendered in the prepar- 
ation of this volume: Victor Electric Company for illustra- 
tions of standard electro-therapeutic apparatus; Clapp-East- 
ham Company for illustrations and the list of parts and ma- 
terials ; Mr. Melville Eastham for a practical working knowl- 
edge of magnetic leakage transformer design and construc- 
tion; and, last, hut not by any means least, Prof. Wm. C. 
Houghton, for many ideas and suggestions, and much un- 
selfish manual labor during the course of experiments which 
made this treatise possible. 

THOMAS STANLEY CURTIS. 



PREFACE TO THE SECOND REVISED AND 
ENLARGED EDITION. 

During the absence of the author of this volume, Mr. 
Thomas Stanley Curtis, the writer was called upon to prepare 
the second revised edition. The first edition of the book was 
made- so complete and the development work done with high 
frequency electricity since the first edition was prepared has 
been so small that there was really little new matter to choose 
from. However, a few thousand words of Mr. Curtis' later|| 
writings on the subject of high frequency, which appeared in 
past issues of ''Everyday Engineering Magazine," were found 
to be suitable and they have been included in the present edi- 
tion together with their accompanying illustrations. 

RAYMOND FRANCIS YATES. 
July, 1920. 



CONTENTS 

CHAPTER I 

THE ALTERNATING CURRENT AT LOW 
AND HIGH FREQUENCIES 

PAGE 

Introduction. What the Alternating Current Is. Change of 
Frequency. Effects of Change in Frequency. The High 
Frequency Current. Characteristics of the High Fre- 
quency Current. Spectacular Demonstrations. The High 
Frequency Current in Medicine. Generation of Ozone 
and the X-Ray. Electrical Cultivation of Plants. Radio 
Telegraphy and Telephony 15 to 26 

CHAPTER II 

HOW THE HIGH FREQUENCY CURRENT 
IS PRODUCED 

Three Practical Methods. The High Frequency Alternator. 
Advantages and Disadvantages. The Direct Current Arc 
Generator. Condenser Discharge Generator. Principles 
Involved. The Kicking Coil Method. Limitations and 
Unique Advantages 27 to 30 

CHAPTER III 

THE HIGH POTENTIAL TRANSFORMER OR 
INDUCTION COIL 

jSome Points in the Construction of High Frequency Apparatus. 
. Principle of the Commercial Transformer. Transformers for 
Condenser Charging. How Arcing is Prevented. Devel- 
opment of the Eastham Magnetic Leakage Transformer. 
The Question of Proper Secondary Potentials. Advan- 
tages of Relatively High and "Low Voltage. Transformer 
Construction. Transformer Designing. How to Calculate 

5 



6 CONTENTS 

PAGE 

Number of Turns, Size of Core, etc. Core Volume. 
Changes Necessary for Use on Various Frequencies. Pro- 
portions of Core. Induction Coils for High Frequency 
Work. How they Differ in Design and Proportion. In- 
duction Coil Design. Kicking Coils. What they Are. 31 to 4f 

CHAPTER IV 
THE OSCILLATION CONDENSER 

Function of the Condenser. What It Is. The Glass Plate 
Variety. Considerations of Weight, Capacity, and Space 
Occupied. A Simple Method of Determining Capacity. 
Forming a Standard Unit. Condensers for Portable Coils. 
The Use of Mica and Micanite. Relative Costs. The 
Murdock Moulder Condenser. Capacities, Sizes and 
Weights. The Oil-Immersed, Glass Plate Condenser for 
Permanent Installation 49 to 53 

CHAPTER V 
THE SPARK GAP 

The Simple Open Gap. Addition of Cooling Flanges. Use 
of Air Blast. The Rotary Spark Gap. Various Types and 
Advantages of Each. Number of Studs or Points Re- 
quired. Speed of Motor. Air Gap between Sparking 
Points. The Quenched Gap. Principles of Operation. 
Simple Types for Amateur Construction. Importance of 
Regulation. Characteristics of the Discharge when 
Quenched Gap is Used. The Rotary Quenched Gap. Pro- 
duction of a High-Pitched Musical Note on 60-Cycle Cur- 
rent. Advantages in Radio Telegraphy . . . . 54 to 59 

CHAPTER VI 
OSCILLATION TRANSFORMERS 

Various Types of Air-Insulated High Frequency Current Trans- 
formers. The Simple Oudin Coil. Various Shapes and 
Proportions for the Secondary. Cones, Cylinders, Cages, 
Spirals, and the Advantages of Each. Various Primary 
Types. Round Conductor, Edgewise-Wound Copper Strip, 
Hollow Tubing, Flat Copper Ribbon, and Stranded Con- 



\ J _ / CONTENTS 



"^^VJiJ^y 



PAGE 

ductor. Couplinig^; The Tesla Type of Coil. How it Dif- 
fers from the Qwdin. Advantajges to be Gained. Tesla 
Secondaries. Means of Mechanical Support. Tesla Pri- 
maries. Proportions and Ratio of Diameter to Length. 
Combined or Double Resonator Type. Coupling. Oil and 
Wax Insulation for High Frequency Coils. Advantages 
and Disadvantages. Advantages of Close Coupling Pos- 
sible. Spirally Wound and Wax Impregnated Coils for 
Portable Outfits. Large Oil Insulated Coils for Testing 
and Other Permanent Installations 60 to 70 

CHAPTER VII 

INDUCTION COIL OUTFITS OPERATED ON BATTERY 

CURRENT 

Ideal Apparatus for the Experimenter. Simple Oudin Reso- 
I nator for Use with a Wireless Transmitter. Interesting 
I Results Obtained with Mediocre Apparatus. Operation of 
t the Outfit. How to Tune the Oscillatory Circuits. Induc- 
' tion Coil Construction. How to Build a Coil Giving a 
Thick, Hot Spark. Core and Primary. Insulation. Sec- 
ondary Winding. Simple Winding Apparatus. Assembly. 
Interrupter and Condenser. Use of Silver Contacts in Lieu 
^' of Platinum. High Tension or Secondary Condenser. 71 to 85 

I CHAPTER VIII 

KICKING COIL APPARATUS 

Possibilities of this Type of Apparatus. Use on Either Direct 
or Alternating Current Circuit. What the Kicking Coil 
Is. Design for Portable Outfit Giving Seven Inch Spark. 
Construction of the Interrupter. The Choke Coil. Data 
for Cores and Windings. The Condenser. Use of Lan- 
tern Slide Cover Glasses. The Oscillation Transformer. 
How the Pancake Coil is Wound. Variable Primary for 
Tuning. Assembly of the Apparatus. Testing and Using. 
Electro-therapeutic Work. Construction of D'Arsonval 
Attachment 86 to 99 

CHAPTER IX 
ONE-HALF KILOWATT TRANSFORMER OUTFIT 
Advantages of a Transformer for Use on Alternating Current 



8 CONTENTS 

PAd 

Winding. Data for All Commercial Voltages and Fre- 
Circuit. Design for a One-Half Kilowatt Magnetic Leak- 
age Transformer. Construction of the Core. Primary 
quencies. Secondary Winding. Assembling and !Mount- 
ing. Oudin and Tesla Coils to Give Eighteen Inch Spark. 
Construction of the Coils. Condenser and Spark Gap. 
Connecting and Using. Protection from "Firing Back" on 
the Line 100 to 11^ 

CHAPTER X ^ 

QUENCHED GAP APPARATUS " 

Peculiar Characteristics of Sparks Produced with the Quenched 
Gap. Increase in Thickness or Volume and Decrease in 
Length. Production of a Flame as Thick as a Broom- 
stick. Design for a Practical Form of Gap. Simple Pat- 
terns Required. Machine Work. Assembly of the Gap. 
Quenched Gap Transformers. Peculiar Characteristics. 
Low Secondary Potential. Data for a Two-Kilowatt 
Quenched Gap Transformer. Specifications for All Com- 
mercial Voltages and Frequencies. Construction of the 
Transformer. Caution to be Observed. Danger of Shock 
from the Low Resistance Secondary Winding. Suitable 
Secondary Condenser. General Hints 114 to 12^ 

CHAPTER XI 
PHYSICIAN'S PORTABLE APPARATUS 

Electro-Therapeutic and X-Ray Apparatus. Requirements of 
the Ideal Outfit. Good Workmanship Required. Dangers 
of a Short Circuit Within the Cabinet. Importance of 
Establishing Confidence of the Patient. Transformer Out- 
fit not Practicable for Amateur Construction. Design for 
Kicking Coil Outfit Within Reach of Builder. Standard 
Electro-Therapeutic Apparatus. Various Types and what 
they Cost. Possibilities and Limitations. Special Direct 
Current Outfits. Apparatus Suitable for Dentists. Large 
Portable Outfits. ' Technical Description and Capabil- 
ities 125 to 131 



CONTENTS 9 

CHAPTER XII 
PHYSICIAN'S OFFICE EQUIPMENT 

PAGE 

Powerful and Efficient Equipment for the Physicians' Office. 
Design for a One-Kilowatt Outfit with Apparatus Mounted 
upon a Table. Advantages of this Form of Construction. 
Imposing Appearance. Accessibility of the Component 
Parts. Construction of the Magnetic Leakage Transform- 
er. Rotary Spark Gap. Stationary Spark Gap. Oscillation 
Condenser. Transformer for Vacuum Tube Work. Oil- 
Immersed Oscillation Transformer for X-Ray Work. 
D'Arsonval Treatment Transformer. Assembly of the Ap- 
paratus. Connecting and Using 132 to 144 

CHAPTER XIII 

A PHYSICIAN'S OFFICE EQUIPMENT MADE WITH 
STANDARD MATERIALS 

Design. Explanation of Operations. Directions for Making 
High Frequency Transformer. Construction of Cabinet. 
Coil for Thermo. Faradic Currents. Price of Alaterials 
Necessary. Design of Impedence. L^se of Apparatus. 

145 to 159 

CHAPTER XIV 
HOT WIRE METER CONSTRUCTION 

I Principle of the Hot Wire Meter. Ease and Cheapness of 
Construction. Measurement of Both Low and High Fre- 
quency Currents with One Instrument. How to Build a 

j Simple Hot Wire Meter. Calibration and Use. . .160 to 165 

CHAPTER XV 

NOTES FOR THE BEGINNER IN ELECTRO- 
THERAPEUTICS 
I Discussion of the Apparatus and the Principles upon which It 
Operates. Relation of Transformer to the Condenser and 
Oscillatory Circuit. The High Potential or Tesla Current. 
Physiological Effects of the High Frequency Current. Re- 



10 CONTENTS 

PAGE 

duction of Blood Pressure. Treatment of Diseases of the 
Skin and Scalp. True Merit of the High Frequency Cur- 
rent in the Practice of Medicine. Stimulation of the Growth 
of Hair. Restoration of the Original Color to Grey 
Hair. Cumulative Effects. The Value of Persistent 
Administration. 166 to 171 

CHAPTER XVI 

PLANT CULTURE WITH HIGH TENSION CURRENT 

Practical Electro-Horticulture or the Cultivation of Plants with 
Electricity. Scarcity of Available Data. Investigation 
Mostly Private. Great Progress Made by Agricultural 
Departments of Schools and Colleges. The Art in the Ex- 
perimental Stage. Electro-culture ^lethods. High Ten- 
sion. Direct Current. High Tension, Low Frequency 
Alternating Current. High Frequency Alternating Cur- 
rent. Cultivation of a Bed of Lettuce. The Aerial Con- 
ductor. Caution Must Be Observed. Construction of the 
High Potential Transformer. Data for All Commercial 
Voltages and Frequencies. Assembly of tlie Apparatus. 
Actual Results Obtained. Report on Experiments at the 
Moraine Farm. Table of Comparative Results Obtained 
with Various Processes of Electro-Culture. . . 172 to 181 

CHAPTER XVII 
HIGH FREQUENCY PLANT CULTURE 

Generation of High Frequency Current for Long Continued 
Periods of Time. The Problem Involved. Careful Work- 
manship Essential. Construction of the Generating Ap- 
paratus. Data for Various Commercial Voltages and Fre- | 
quencies. Building of the Transformer. Assembling and 
Mounting. Construction of the Condenser. Provision for 
Cooling. The Self-Cooling Spark Gap. The Oscillation 
Transformer. Installation of the Apparatus. The Trans- 
former Shed. Switches and Control Devices. Protection 
from Accidental Shock. Wiring the Plot to be Cultivated. 
Ground Connection and Overhead Net Work. Operation 
of the Apparatus. Time of Treatment. Value of Com- 
parative Data 182 to 20v^ I 



CONTEXTS 11 

CHAPTER XVIII 
FURTHER NOTES ON PLANT CULTURE 

PAGE 

How to Use a Standard Radio Transmitter for Plant Culture 
Work. The Distributing System. Construction Difficul- 
ties. Alaking Wire Net Work. Vegetables to' Plant. 
Apparatus Required. jMushroom Growing. . . 204 to 211 

CHAPTER XIX 

A FOREWORD OX THE CONSTRUCTION OF ELECTRI- 
CAL APPARATUS FOR THE STAGE 

High Tension Electrical Stagecraft. Opportunities of High 
Potential Electricity for the Professional Entertainer. 
Chance to Improve upon Past Offerings. Importance of 
High Frequency Apparatus. Points to Consider before 
Starting Work. Cost and Weight of Apparatus. Differ- 
ence Between the Lecturer and the Vaudeville Artist. Cur- 
rent Required and Difficulties of Obtaining It. Where 
and How to Build the Apparatus. The Home Workshop 
and Its Equipment. Some Work Done Outside if Large 
and Expensive Tools are , not Available. Advantages of 
Doing Work at Home. Working Drawings and Blue- 
prints. Need for Practical Working Knowledge of Sub- 
ject. How to Obtain this Knowledge. ^Mathematics Un- 
necessary 212 to 217 

CHAPTER XX 

CONSTRUCTION OF LARGE HIGH FREQUENCY 
APPARATUS 

Design for a Resonator Producing a Five-Foot Spark. De- 
tails of Construction. Building the Secondary Cylinder. 
The Winding. Building the Primary. Assembly of the 
Coil. Connecting Cable and Clips. The High Potential 
Transformer. Design for a Four-Kilowatt Magnetic Leak- 
age Instrument. Building the Core. Forms for Winding 
Primary and Secondary. Insulation. Assembly of the 
Transformer. Construction of the Rotary Spark Gap. 
Spark Gap Muffler. The Oscillation Condenser. Coating 
the Plates. Building Up Units. Connections. Setting Up 



12 CONTENTS 

PAGE 

and Operating the Apparatus. The Switch Board. Pre- 
vention of Kick Back. Tuning and Adjustment of the 
Apparatus 218 to 238 

CHAPTER X'XI 
LARGE TESLA AND OUDIN COILS FOR THE STAGE 

Specifications for Large Oscillation Transformers of the Port- 
able Air-Insulated Type. Tesla Transformer for the Pro- 
duction of a Fifty-Inch Spark. Details of Construction. 
Oudin Resonator for the Production of a Short but Very 
Thick Discharge. Mounting the Apparatus. Provisions 
for Packing and Shipment 239 to 246 

CHAPTER XXII 
CONSTRUCTION OF A WELDING TRANSFORMER 

Transformer to Deliver a Current of Low Voltage and very 
Great Amperage. Heating a Quarter-Inch Iron Rod to 
Incandescence. Building the Transformer. Suggestions 
for Handling the Heavy Secondary Wire. Insulation. 
Assembly and Mounting. Experiments Using a Current 
of 250 Amperes. Special Copper Tongs or Pliers. Alaking 
Flexible Cable to Carry the Heavy Current. Burning Up 
a Heavy Bar of Steel. Welding Two Pieces of Iron Rod 
Held in the Hands. Spot Welding of Sheet Iron. Melt- 
ing Metals in a Crucible to Show Principle of Electric 
Furnace. Suggestions for Effective Stage Setting. Par- 
ticularly Startling and Spectacular Experiments to Close 
the Entertainment 247 to 25S 

CHAPTER XXIII 
HINTS FOR THE ELECTRICAL ENTERTAINER 

Preparation of the Lecture. Snap and Vigor Necessary. Edu- 
cation of the Public Far Advanced in Recent Years. Class 
of Audience Must Receive Careful Consideration. Com- 
parison of Well-Read Chautauqua Assembly with Audience 
Found in High Class Vaudeville Theatre. Vaudeville Au- 
dience Demands to be shown. Experiments must Speak 



CONTENTS 



13 



PAGE 

for Themselves. Method of Presentation for Typical Lec- 
ture Audience. Touch of Comedy of Great Value with 
Theatre Audience. Short Introduction Preferable. Im- 
pressive Opening Necessary. Suggestion for Successful 
Program. "Trying it on the Dog." The Matter of Re- 
hearsals. Selection of Experiments. Time of Act. How 
to Present the Offering on the Stage or Lecture Platform. 
Specimen Program with Outline of Experiments and 

Lecture 256 to 263 

Useful Tables 264 to 266 




p. ^{,^76' 



CHAPTER I. 

THE ALTERNATING CURRENT AT LOW AND 
HIGH FREQUENCIES. 

While the manuscript for this book was being pre- 
pared, the author was approached by a caller who intro- 
duced himself as an enthusiastic experimenter and a reader 
of all manner of practical books. This gentleman explained 
that he was an armature winder by trade, and that he 
wished to take up high tension work solely as a hobby. He 
was possessed of but little knowledge of mathematics and 
had been unable to understand the many books on trans- 
( former design and construction that he had purchased. 
I A few minutes' conversation with this caller brought 

I to light some important points which since have prompted 
a radical and wholesale change in the method of treat- 
I ment. Half a dozen pointed questions suggested the in- 
troduction to the general -subject that is offered in the next 
few paragraphs. 

What the Alternating Current is. — An alternating cur- 
rent is one that periodically changes its direction of flow a 
I certain number of times per second. It is the reverse of the 
I direct current which is assumed to leave the battery or dy- 
; namo at the positive pole and return by way of the negative 
pole. With the alternating current, the terminals of the 
machine are alternately positive and negative. This char- 
I acteristic is well shown in the diagram, Fig. 1, which may 
be assumed to show the course taken by a current leaving 

IS 



16 



HIGH FREQUENCY APPARATUS 



the terminals of an alternating current generator having 
four field poles and having its armature or ' rotor'* driven 
at 1800 R.P.M. This machine v^ould be termed a 60-cycl 
alternator because the current it delivers v^ould make 60 
complete cycles or 120 alternations in a space of one second. 

With reference to Fig. 1, let us assume that A repre- 
sents the current as it starts from one collector ring of the 
machine. Following the direction indicated by the arrow, 
we find the current rises in voltage until it reaches its peah 
at 5. The value then falls back to zero as the current re- 
turns to the other collector ring, C At this point the arma- 



moA/mam 
'J[ \ potent /a/ 



zero 




poteJif/at 



ma//mi/rr> 
jXftent/a/ 



Fig. 1. — Diagram showing how an alternating current periodically reverses its 

direction of flow 



ture or rotor of the machine passes to the next set of field 
or stator poles and the current starts out over its circuit 
again, but in the reverse direction. For convenience, this is 
shown as below the zero line in the illustration. Leaving 
C, the current rises to the maximum at D and then returns 
to £. 

The period of time taken in -the passage from A to B 
is just 1/60 second ; in this space of time the current has 
made a complete cycle of two alterations, one in a positive 



THE ALTERNATING CURRENT 17 

and the other in a negative direction. In one second of 
time, it will have made 60 complete cycles ; it i > therefore 
called a 60-cycle current. 

Change of Frequency. — Now let us assume that the al- 
ternator be supplied with eight field or stator poles instead 
of four. As a reversal of current occurs when the rotor 
windings pass from the influence of one pair of stator poles 
to the next pair, it is obvious that to double the number of 
stator poles is to double the frequency, if the speed at 
which the armature is driven remains the same in each 
case. On the other hand, precisely the same result is ob- 
tained if the number of poles remains fixed and the speed 
of the rotor is doubled. Therefore, the matter sums itself 
up into a simple formula which will be useful to the worker 
if he will but understand it and not fear it as some intang- 
ible form of ''mathematics." The formula is: 

2X60 
' Frequency := 



R.P.M. X Number of Poles 



Therefore, if we know the number of poles of a given 
machine and the speed at which it is driven, we may multi- 
Jply the number of revolutions per minute by the number 
^f poles and divide this product by 120 to find the fre- 
quency of that particular machine. 

I On the other hand, suppose we know the number of 
poles and we are required to produce a certain frequency 
from a given machine; we must determine the number 
pf revolutions at which the rotor must be driven. This 
ormula is: 

2 X 60 X Frequency 
R.P.M. = 



Number of Poles 



18 



HIGH FREQUENCY APPARATUS 



To simplify the first formula into a form where it i 
ready for use at a moment's notice without any calculation, 
we may say that the number of cycles per revolution will 
be equal to the number of poles divided by 2. To use this, 
let us take the case of the four pole machine. Four di 
vided by 2 is 2. Therefore, the machine will deliver two 
cycles to every complete revolution of the rotor. If the 
speed is 1800 revolutions per minute or 30 per second, the 
frequency is 2 times 30 or 60 cycles per second. 

Effects of Change of Frequency. — For commercial use 
such as lighting lamps and operating motors, the 60-cycle 




Fig. 2. — A motor-gcneratur lor cl.angir.g direct current to alternating current 

current is in general use in the United States. Certain 
parts of the country still use 125 and 133-cycle currents 
and in Canada the 25-cycle current is much in evidence. 

A change in the frequency of the current necessitates 
profound changes in the apparatus it is intended to oper- 
ate. It is not within the province of this work, however, 
to touch upon the alterations necessary in motors in order 
that they may be adapted for various frequencies. Suf- 
fice it to say that in the case of transformers, which ^Tc 
closely identified with the apparatus described, any change 



THE ALTERNATING CURRENT 19 

in the frequency of the current necessitates a corresponding 
change in the windings of the transformer. 

Generally speaking, one of the higher frequencies is to 
be preferred for transformer work, for the core may be 
lighter and smaller, and the instrument is consequently 
cheaper and easier to build. Therefore, if the worker in- 
tends to generate his own alternating current, he may well 
employ an alternator producing a 120-cycle current at 
moderate speed. As a rule, however, some form of alter- 
nating current supply is available and, in such event, the 
experimenter will, of course, find it cheaper and better to 
so design his apparatus that it will operate in a satisfactory 
manner on the circuit at hand. 

In the various descriptions of transformers w'hich fol- 
low in later chapters, the data for all standard frequencies 
are given in order that the worker need not make computa- 
tions unless he so desires. In addition to this, one entire 
chapter is devoted to a simple explanation of the principles 
of transformer design, and, from this explanation, the av- 
erage worker will be enabled to w^ork out any special de- 
sign that may appear desirable. 

In the case of direct current supply a motor-generator 
of the type shown in Fig. 2 is sometimes used. This con- 
sists of an alternating current generator driven by a direct 
current motor. Both armatures are mounted on the same 
jShaft in the machine illustrated. 

I The High Frequency Current. — When an alternating 
'current is made to change its direction of flow many thou- 
sands of times per second, it is termed a "high frequency 
current.'' The precise figure at which this term is properly 
jappHed is not very clearly defined but it is usually placed 
at the mark of 10,000 cycles per second. From this, it 
may extend into the hundreds of thousands or perhaps 
^millions of cycles per second. How this current, w^hich os- 



20 HIGH FREQUENCY APPARATUS 

cillates with such inconceivable rapidity, is produced will 
be duly explained in the next chapter, but first of all let 
us consider the peculiar characteristics of which it partakes 
and the uses to which it may be put. 

Characteristics of the H. F. Current. — For the serious 
experimenter and student of modern electricity, there is 
no more fascinating study than that of the electric current 
at high potential and high frequency. The phenomena 
which may be exhibited through its agency are at once 
spectacular and startling, of inconceivable beauty and 
grandeur, and, in practical applications, of the greatest 
utility and importance. While the larger types of appara- 
tus demand that the utmost care and the finest materials 
be- used in the construction, the youthful experimenter may 
satisfy his craving for immediate results by building tem- 
porary apparatus of the crudest construction imaginable 
and still obtain effects bordering upon the marvelous. I 

When the electric current is made to oscillate or change * 
its direction of flow several thousand times per second, it 
partakes of some astonishing characteristics. All of the 
preconceived theories of electricity as applied to the com-' 
mercial current are overthrown and the phenomena ex- 
hibited are contradictory in the extreme to the conventional 
ideas of the everyday electrical worker. For example, if an 
alternating current of the commercial sort having a fre- 
quency of 60 or 125 cycles per second, be passed through 
the human body, a muscular contractive effect is produced 
and the sensation of an electric '*shock" is felt. If the volt- 
age of the applied current should be higher than the hun- 
dred mark, the shock is unpleasant and perhaps dangerous ; 
let it reach 1,000 volts or perhaps even half that amount, 
and the shock is in most cases fatal. On the other hand, 
if the current be made to oscillate or change its direction 
of flow with a frequency of 10,000 or more cycles per sec- 



THE ALTERNATING CURRENT 21 

ond, it may be applied to the body without danger or even 
discomfort at potentials running well into the tens of thou- 
sands. Let the frequency be increased still further, say 
into the millions, and the sensation of shock and muscular 
contraction is quite absent. Its place is taken by one of 
gentle warmth. 

Spectacular Demonstrations. — The importance of this 
one peculiarity alone will be appreciated by those who 
have seen the self-styled electrical marvels upon the stage. 
Their claims to the effect that they are ''taking thousands 
of volts through their bodies'' are perhaps well founded 
for the presence of a spark several inches long is pretty 
good evidence of a very high potential. It is usually con- 
, ceded that every inch of spark between points through 
. the air represents a potential of between fifteen and twenty- 
five thousand volts. The secret of the performer's apparent 
power rests solely with the high frequency current. 
I Perhaps the reader has seen one of these entertainers 

I charge the body of an assistant to the point where a spark 
< several inches in length may be drawn from the fingers, 
chin, elbow, or even the tongue. A tuft of cotton or tissue 
paper held in the spark is immediately ignited, or perhaps 
the performer may light the tip of his cigarette with the 
spark taken between his finger and the body of the assistant. 
Possibly the performer may grasp the terminal of his ma- 
chine with one hand while the other holds a wire leading 
to an ordinary incandescent lamp ; the assistant touches the 
remaining terminal of the lamp and the current is turned 
on. The lamp filament becomes red and perhaps white 
hot, finally burning out completely with the current passed 
through the bodies of the performer and his man. 

The stage may be darkened and the terminal of the 
apparatus connected with the body ; as the current is turned 
on, the extremities of the body are seen to glow with a 



22 HIGH FREQUENCY APPARATUS 

weird blue light. As the hand is raised above the head, 
streamers of purplish fire dart from the finger tips. A 
vacuum tube brought to within a distance of several feet 
from the body lights up with its characteristic glow even 
though there is no connection with the performer's body 
or the apparatus. 

All of these experiments and hundreds of others may 
be performed with comparatively simple and inexpensive 
apparatus that is well within the reach of the average ama- 
teur mechanic. If the reader aspires to greater heights, he 
may build apparatus with which great, long sparks may be 
produced. 

The High Frequency Current in Medicine. — The high 
frequency current, when applied to tlic human body through 
suitable electrodes and other appurtenances, can be made 
to produce the most profound physiological effects. Ap- 
plied through a glass electrode from w^hich the air has been 
exhausted, the current stimulates the circulation of the 
blood, bringing it to the surface and increasing nutrition. 
Persistent application of the vacuum electrode to the scalp 
at certain intervals will restore tlie original color to grey 
hair. On the scalp of a partially bald patient, repeated 
applications will promote the Lrowth of new hair if the 
roots have not been totally destroyed. 

Placing the patient in a chair having a metallic plate 
beneath its seat and behind the back, the physician may ad- 
minister the high frequency current in the form of treat- 
ment known as auto condensation and thereby reduce the 
blood pressure in cases of arteriosclerosis. The same treat- 
ment is being successfully used in the reduction of super- 
fluous flesh. 

The general effect on the patient is a tonic one and in 
practically every case reported, the patient has been 
brightened up, given added vieor and cheerfulness, and, in 



THE ALTERNATING CURRENT 23 

fact, has exhibited all of the favorable efifects of a powerful 
tonic without sustaining any of the unfavorable after ef- 
fects of a stimulant. 

While on the subject of the medical application of the 
high frequency current, it may be well to point out the 
fact that while no ill effects are likely to be experienced 
from the treatment in the hands of an unskilled operator, 
continued applications intended to produce a medicinal ef- 
fect upon the body should certainly not be given by the 
layman without first having had the advice of a physician. 
The two primary modes of treatment, i. c, the vacuum elec- 
trode and the auto condensation, produce diametrically op- 
posite eft'ects. The electrode treatment tends to increase 
the blood pressure while the auto condensation tends to 
reduce it. It is obvious, therefore, that the auto condensa- 
tion should never be applied except in cases where normal 

( or hyper tension is indicated. After the examination has 
been made and the treatment prescribed, there is no reason 
why the actual administration should not be given by the 

\ layman if the physician keeps a watchful eye on the prog- 
ress at suitable intervals between treatments. 

The Generation of Ozone and the X-Ray. — For the 
physician or the experimenter, there is perhaps no form of 
X-Ray apparatus better adapted to light office or labora- 
tory use than the high frequency coil. It is safe, convenient 
and powerful and for all cases where very short exposures 
through the heavier portions of the body are unnecessary, 
it will meet the requirements admirably. True, the X-Ray 
is never quite safe in the hands of anyone other than a 
skilled operator having years of experience on his shoulders. 
The ray generated by a tube excited with a high frequency 
current is, however, less liable to produce the characteris- 
tic burn than is that produced by any other means. Just 
why this is so, is not definitely known, but the experience 



24 HIGH FREQUENCY APPARATUS 

of the past few years indicates beyond a doubt the truth 
of the statement. 

A high frequency coil to produce an eight-inch spark 
of a quality adapted to light X-Ray work can be built in 
the home workshop at only a fraction of the cost of an 
induction coil to do the same work. Furthermore, the 
high frequency apparatus is simple in construction and op- 
eration and it can be depended upon to do its work without 
the annoying delays incident to the usual induction coil 
with its troublesome interrupter and the ever-present dan- 
ger of a serious breakdown of the insulation. 

As a generator of ozone for medicinal purposes, the 
high frequency coil is particularly energetic and efficient. 
When the discharge terminals of the coil are separated be- 
yond the normal sparking distance, great volumes of ozone 
are liberated in the space filled with a crackling brush dis- 
charge. When the vacuum tube electrode is passed over 
the body, the ozone is liberated at the point of contact. For 
purposes of inhalation, a simple apparatus consisting of 
vacuum electrode surrounded by an outer wall of glas: 
with an air space between can be made to produce the gas 
in ample quantities and with the additional advantage that 
it may be collected and administered to the patient through 
a suitable rubber tube and mouthpiece. Furthermore, this 
simple appliance permits one to pass the gas through 
small quantity of oil of eucalyptus which tends to remov' 
the nitrous oxide that invariably accompanies ozone gen- 
erated by the electric spark. 

Electrical Cultivation of Vegetation. — The high fre- 
quency current, when sent through a network of wires 
above a plot of ground, has the peculiar property of stimu- 
lating the plant life in the earth beneath the wires. Just 
why this should be so is not definitely known ; while vari- 
ous theories have been advanced, it is possible that one and 



1 



THE ALTERNATING CURRENT 25 

all may be faulty and it is not within the province of this 
book to offer theories. The apparatus required for the cul- 
tivation of plants on a small scale is neither elaborate nor 
costly although it must be made rather rugged in electrical 
construction to withstand the strain of almost continuous 
operation for hours at a time. 

In a later chapter the data for the apparatus required 
for the cultivation of a one acre plot in the open is given ; 
in addition to this, notes 'on the conduct of experiments with 
potted plants indoors are given as are also a few sugges- 
tions for hot-house work with both vegetables and flowers. 

The electrical cultivation of plants is entirely practical 
if a source of cheap electric power is available. On the 
small farm where water power or even gasoline engine 
power is developed, the electric current may be generated 
at very low^ cost in quantities sufficient for practical work. 

The experiments have their commercial side as well as 
their purely experimental. Crops may be forced to an 
early maturity with a marked increase in the flavor and 
tenderness. Lettuce is particularly susceptible to the in- 
fluence of the current, while radishes and beets follow 
closely. For fancy fruits and vegetables the process is 
productive of results which add materially to the profits 
ordinarily to be made. 

, Radio Telegraphy and Telephony. — Beyond a doubt, 
ithe most popular and the best known application of the os- 
cillatory current is in the field of radio telegraphy and tele- 
'phony. Every village seems to have one or more amateur 
jwireless telegraphs. 

I The oscillatory current, when vibrating within a certain 
Irange of periodicities, sets up electromagnetic waves in the 
(ether if it be sent into an aerial or overhead wire which 
'is insulated from the earth. These waves, which resemble 
light waves in point of speed but which are quite invisible, 



i 



26 HIGH FREQUENCY APPARATUS 

are radiated in all directions at a pressure of the radio tel 
graph key. 

The apparatus described in this book is admirably 
adapted for purposes of radio telegraphy and some of the 
transformers, condensers and spark gaps represent the best 
and most modern practice in the construction of radio trans- 
mitters. 



II 



CHAPTER II. 

HOW THE HIGH FREQUENCY CURRENT IS 
PRODUCED. 

There are but three practical methods by means of 
which the high frequency current may be generated. In 
one of these methods, an alternating current generator 
having a very large number of stator pole pieces is em- 
ployed ; this is essential in order that the speed at which the 
rotor must be driven may be kept within reasonable limits. 
Even so, the speeds of most of the experimental machines 
built thus far have been .as great as 10,000 R.P.M. and 
the reader's practical knowledge will doubtless tell him 
that a heavy, composite mass of metal, driven at this speed, 
introduces complications that are very likely to result dis- 
astrously should anything go Avrong. The maximum fre- 
quency obtainable by this method is about 100,000 cycles 
per second and this frequency, with a useful output of cur- 
rent, is to be obtained only through the use of a very costly 
and dangerous machine. The high frequency alternator 
method, while it undoubtedly possesses some positively 
unique advantages in radio telegraphy and telephony, is 
scarcely a piece of apparatus that comes within the scope 
of this book. 

The second method is by means of the direct current 
arc. • When an ordinary arc is shunted by a suitable ca- 
pacity and inductance, oscillations are set up in the circuit. 
A secondary added to the primary inductance or helix will 

27 



28 HIGH FREQUENCY APPARATUS 

have induced in it a high frequency current similar to that 
oscillating in the primary circuit. By means of a suitable 
adjustment of the ratio existing between the turns in the 
two coils, the potential delivered at the secondary terminals 
may be increased practically at will. 

The most familiar use of the arc as a high frequency 
current generator is in the field of radio telephony. The 
purity of the wave generated by the arc renders it particu-, 
larly well adapted to this use. For purposes of demon- 
stration, however, the arc generator is not capable of de- 
livering a sufficiently large output. With all due respect to 
the method in the work for which it is best adapted, we 
shall therefore recommend that the experimenter discard 
it, using in its stead, the condenser discharge form of gen- 
erator, a detailed description of which follows. 

Condenser Discharge Generator. — It is assumed that 
the average reader of this book will be familiar with the 
elementary principles of wireless apparatus. Granting this, 
it is. of course, reasonable to believe that such readers will 
understand how an oscillatory current is set up in a circuit 
comprising an inductance or coil of wire, a capacity or 
condenser, and a spark gap. The condenser is charged with 
a high tension current from any convenient source such 
as a transformer or induction coil, and when the potential 
stored up in the condenser reaches a critical value, the air 
in the gap between the spark gap electrodes can no longer 
stand the strain, and the condenser discharges across the 
gap in a succession of crashing sparks. As the current 
from the condenser crosses the gap in one direction, it lit- 
erally over-reaches itself just as a pendulum swings past the 
neutral point when given a push with the hand. When the 
first rush of current passes in one direction, a reversal of 
the cycle occurs and a second rush in the opposite direc- 
tion is effected. This operation is repeated many thou- 



HIGH FREQUENCY CURRENT 29 

sands of times per second, the discharge gradually dying 
down until the potential across the condenser has been low- 
ered to such an extent that the spark can no longer jump 
the air gap. The Condenser immediately takes a fresh 
charge from the transformer and the entire cycle of opera- 
tions is repeated. It will be understood that all of this 
passes in an infinitesimal fraction of a second, the charge 
and discharge of the condenser taking place so rapidly that 
the observer can detect no change in the solid spark which 
appears continuously to fill the gap. 

As the current surges back and forth through the in- 
ductance, which is merely a coil of a few turns of very heavy 
wire, a similar current is induced in a second coil of wire 
placed in the same plane as the first. A slight increase 
in the number of turns in the secondary over those in the 
primary will result in a very large increase of potential 
between the secondary terminals. 

Unlike the low frequency or commercial transformer 
the high frequency or oscillation transformer requires no 
iron core whatever ; indeed, the presence of iron in the cen- 
ter of the windings is not to be considered as it would be 
detrimental to the successful operation of the transformer. 

From this the reader will note that in order to produce 
a high frequency current of practically any desired potential 
it is only necessary to combine two coils of insulated wire 
of the proper proportions and number of turns v/ith a con- 
ventional transformer, condenser and spark gap. 

The Kicking Coil Method. — The operation of a high 
tension transformer for the charging of a condenser neces- 
sitates an alternating current. There are certain cases 
wherein it is desirable to produce a high frequency current 
where direct current only is available. This is particularly 
true in the case of electro-medical apparatus which must 
frequently be used at the patient's bedside. For this type 



30 HIGH FREQUENCY APPARATUS 

of apparatus, a simple modification of the condenser dis- 
charge principle is available. This method utilizes what 
is known as a ''kicking coil." 

A kicking coil is a solenoid of coarse copper wire wound 
upon a laminated iron core. If a direct current be sentj 
through this winding, and the circuit broken suddenly, a 
pronounced flash will occur at the break of contact. The 
high potential represented by this flash is induced by the 
self-induction of the coil wound on the iron core. Under 
favorable circumstances the instantaneous voltage gener- 
ated may reach from several hundred to considerably over 
a thousand volts. This potential is, of course, quite suffi- 
cient to charge a condenser, and it is only necessary to pro- 
vide some suitable means for rapidly making and breaking 
the circuit with condenser and inductance in series in order 
to generate a high frequency current quite similar to that 
produced with the apparatus described in the precedingl 
section. 

Experiment has shown that a substantial vibrating in- 
terrupter with heavy silver contacts serves the purpose ad- 
mirably. The vibrator is actuated by means of the magne- 
tism in the core of the kicking coil. 



CHAPTER III. 

THE HIGH POTENTIAL TRANSFORMER OR 
INDUCTION COIL. 

As the reader will have inferred from the preceding 
chapter, the condenser discharge principle is employed in 
the construction of all of the apparatus described in this 
work. While the use to which each particular outfit is to 
be put governs, in a large measure, the actual construction 
and design of the component parts of the apparatus, the 
basic principle is quite the same in each case. Granting 
this, each outfit will comprise the following units: 

The Transformer or Induction Coil w^hich converts the 
low voltage current available from the lighting circuit, or 
perhaps a battery, into a high voltage current suitable for 
charging. 

The Condenser, which is composed of alternate sheets 
^ of metal and glass or other material having a high dielectric 
value. The condenser discharges its load of electric cur- 
rent at high pressure across 

The Spark Gap, which is composed, essentially, of 
metallic electrodes, having accurately turned faces held in 
the same plane by means of suitable supports. In series 
with the spark gap and condenser is the primary of 

The Oscillation Transformer, which comprises two 
coils or helices of copper wire. One of these coils, the 
primary, is composed of a few turns of thick wire, while 
the secondary may have from ten to one hundred times as 
many turns of fine wire. 

31 



32 HIGH FREQUENCY APPARATUS 

A few general suggestions relative to each of these 
units and their relations one to the other will, it is believed, 
be conducive to a clearer understanding of the detailec 
directions which follow in later chapters. No attempt will 
be made, in the present chapter, to offer details of con-| 
struction such as dimensions of the parts, as this feature 
is covered specifically in the directions given in succeeding 
chapters, each of w^hich is devoted to a complete descriptior 
of a certain type of outfit. The object of the genera^ 
information in this and the following chapter is to afford 
the reader, who has delved but slightly into the intricacies 



Fig. 3. — Simple open core transformer. Core is represented by C, primary by 

and secondary by S. 



1 



of high tension electrical work, an intelligent insight int 
the basic principles of design and construction of the sev- 
eral units which comprise the outfit. A 
Transformers. — The transformer is essentially an al" 
ternating current device. In its simplest form, it consists 
of a core, C, Fig. 3, of laminated iron, a primary winding 
of insulated copper wire, P, and over this a secondary wind- 
ing, vS", also of insulated copper wire. An alternating cur- 
rent sent through one winding induces a similar current in 
the second winding. A variation in the ratio existing b^ 
tween the turns of the two coils, produces a corresponding 
change in the induced voltage. 



HIGH POTENTIAL TRANSFORMER 



33 



Such a transformer is known as an ''open core'' instru- 
ment because the magnetic Unes of force set up in the 
straight iron core must reach around through the air as 
shown in Fig. 3 to complete the magnetic circuit. A modi- 
fication is shown in Fig. 4 which illustrates a method by 
means of which the windings of the transformer are par- 
tially surrounded by iron. This provides a ready path for 
the lines of force with a large increase in the efficiency of 
the instrument. Such a transformer is said to have a closed 
core. 




Fig. 4. — Showing principle of closed core transformer. Lines of force p:.ss 
through the closed magnetic circuit instead of through the air as in Fig. 3 

There are many modifications of the closed core trans- 
former, all of which have merits peculiar to the uses to 
which they are put. For lighting and power work, it is 
desirable to have the primary and secondary windings as 
closely ''coupled'' as possible and to this end most power 
transformers have very compact cores which almost cover 
the windings. The effect of this close coupling is to im- 
prove the ^'regulation" of the transformer, i. e,, to reduce 
the fluctuation in voltage from no load to full load to a 
minimum. This type is shown in Fig. 4. 

Transformers for Condenser Charging. — In the early 
days of radio telegraphy, when transformers were first used 



34 



HIGH FREQUENCY APPARATUS 



for the charging of condensers, the experimenter knew but 
little of the requirements of the process. The only high ten- 
sion transformers available were of the power variety with 
closely coupled primary and secondary, and the first trials 
of these gave such promising results that the workers were 
induced to carry on an extensive line of research with 4 
view to improving the apparatus. 

One great difficulty was experienced from the start 
A glance at Fig. 5 shows that the secondary terminals of 
the transformer are shunted by the spark gap, which in 
turn is shunted by the condenser and primary of the oscil- 




Fig. 5. — Typical oscillatory circuit showing how high frequency current is 
generated by means of the condenser discharge method 

lation transformer in series. When the condenser dis- 
charges across the spark gap, the discharge- produces a 
short circuit for the secondary current in the transformer j 
after the spark has died away. This causes an arc to form i 
with the result that the condenser cannot charge again as] 
it should. The close coupling of the windings tends to [ 
hold the secondary voltage at its maximum when the short 
circuit occurs, ^ 

Various experiments were tried to prevent the forma-J 
tion of the arc, and among these may be mentioned a mag- 
netic blow out, which aided in quenching the arc; a blast 



HIGH POTENTIAL TRANSFORMER 



35 



of compressed air between the spark gap electrodes, which 
literally blew "out the arc as soon as it formed ; and various 
devices which mechanically separated the electrodes to a 
point where the arc was extinguished. The most familiar 
form of the latter device is the common rotary spark gap. 

As the work progressed, the experimenters discovered 
that by placing an impedance coil, consisting of a sinele 
winding of copper w^ire on an iron core, in series with the 
primary of the transformer, the arcing was materially les- 




'UI1AKA6C, 



Fig. 6 — Typical closed core transformer arranged for power and lighting circuits. 

Close coupling of primary and secondary prevents excessive 

drop in secondary voltage when load is applied 



sened and the various blow-out devices were rendered un- 
necessary to a certain extent. This procedure is illustrated 
in Fig. 5, which shows the impedance coil in series with 
the primary of the transformer, the windings of which are 
closely coupled. This was the first step in the direction of 
the celebrated "Type E'' wireless transformer which was 
patented by Mr, Melville Eastham and which has been 
copied in various forms by dozens of manufacturers since 
its introduction. 

The design of the ''Type E" transformer introduces the 



36 



HIGH FREQUENCY APPARATUS 



very quality that the makers of power transformers seek 
to avoid, namely, magnetic leakage in the core. When 
the secondary of such a transformer is short circuited by 
the spark, the potential instantly drops to so low a value 
that the arc dies out of its own accord ; indeed, it is doubtful 
if any appreciable arc forms at all. 

The principles of the magnetic leakage transformer are 
shown in Figs. 8, 9 and 10. In Fig. 6, the primary and sec- 
ondary are seen to be mounted upon separate legs of the 
rectangular iron core. This loosens the coupling to such an 




Fig. 7. — Transformer _ with closely coupled primary and secondary and the 
impedance coil in series with primary to prevent arcing at spark gap 

extent that magnetic leakage is set up in the space be- 
tween the windings and around the outside of the core as 
shown by the lines in the drawing. This leakage diverts 
a portion of the total flux from its path through the cores 
inside the windings, and when the abnormal load comes 
on the secondary, the potential suffers a tremendous drop 
as the regulation is intentionally poor. 

In Fig. 9, the primary and secondary are still farther 
separated by being placed upon the short legs of the core 
instead of the long ones as shown in the preceding figure. 



HIGH POTENTIAL TRANSFORMER 



Zl 



This is carryin^^ the point still farther. In Fig. 10, we have 
the true Type E instrument in which a tongue of iron pro- 
jects from one leg of the core between the windings, and 
nearly makes contact with the opposite leg. This intro- 
duces a partial magnetic shunt that serves every purpose 
of the external impedance coil and which has some marked 
advantages over the latter device. 

With a correctly proportioned magnetic leakage trans- 
former, brought to resonance by a suitable condenser con- 
nected in the oscillation circuit, the arcing at the gap is 




Fig. 8. — Transformer with primary on one leg and secondary on other leg of 

core to introduce greater magnetic leakage. The first step in the 

development of the resonance type of transformer 



reduced to a minimum and the discharge partakes of a 
clear ringing tone not to be heard in other types of 
equipment. 

In addition to this marked advantage, the magnetic 
leakage transformer can be made to attain a degree of 
efficiency and a power factor not possible in the ordinary 
combination with its impedance Qoil. 

Secondary Potentials. — The proper potential for the 
secondary in the case of the resonance transformer (the 
term that will henceforth be applied to the low-frequency 



38 



HIGH FREQUENCY APPARATUS 



alternating current transformer designed for condenser 
charging) will depend upon the condenser with which it 
is to be used and also upon the type of spark gap employed. 
Since the introduction of the Federal radio telegraphic 
laws which govern the wave length of amateur stations, 
the tendency has been in the direction of higher potentials 
for wireless telegraphic work. The higher potential per- 
mits a smaller condenser to be used. For other high fre- 
quency work, however, there is no particular advantage to 
be derived from the high voltage secondary and its use in- 
volves certain electrical and mechanical difficulties that are 
expensive and annoying to surmount. 




Fig. 9. — Primary and secondary on short legs of core and widely separated to 

increase magnetic leakage. This construction renders external 

impedance coil unnecessary 

The most satisfactory potentials, in the authors experi- 
ence, have been from 4,000 up to 12,000 in transformers 
ranging in size from J4 k.w. to 3 k.w. This range of po- 
tential, with a .03 mfd. condenser has been found quite suit- 
able in the construction of many sets of apparatus. 

With the quenched type of spark gap, a totally differ- 
ent condition is met. Secondary potentials as low as 900 
to 1,000 volts are excellent in the case of small transformers 
of capacities ranging from J4 to j^ k.w. For the larger 
sizes, the potentials may run up from 2,000 to 3,000 volts. 
The quenched gap, which will be specifically described 



t 



HIGH POTENTIAL TRANSFORMER 



39 



later, is exceedingly short and a much lower potential is, 
accordingly, in order. 

k Transformer Construction. — In each chapter of this 
ok, wherein a set of apparatus is described, the complete 
specifications for the construction of the transformer are 
given. The object of this discussion will, therefore, be to 
cover only briefly the essential principles of the construction. 
The transformer core in each case should be of thin 
sheets of silicon steel, .014 in. thick, and made expressly for 
use in transformers and other alternating current appara- 
tus. It is practically as cheap as the so-called transformer 




Fig. 10. — Type E transformer with tongue of iron to increase magnetic leakage 

between windings 

iron and, if results count, it is much cheaper than stove-pipe 
iron. 

The construction of the core is simple. The silicon 
steel can be bought in sheets or, preferably, in pieces cut 
to size and ready to assemble. The rectangular pieces are 
placed one upon the other to make piles of the required 
thickness for the assembled core and then firmly gripped 
with a binding of tape. 

The windings are made on simple wooden forms, either 
in a lathe or else on a hand winding device. The winding 
is invariably that known as the layer method. The ''pie'' 



40 HIGH FREQUENCY APPARATUS 

winding, described in so many of the older books on radio 
construction, has been tried out thoroughly by the author 
and by many of his colleagues ; the result is a wholesale 
denunciation of it, bag and baggage, as it were. True, a 
modification of the pie winding is seen in many of the de- 
signs presented in this book but the pertinent fact is that 
the directions do not call for an annulus of wire, held to- 
gether by wax, and with the turns laid on any-which-way. 
The sections may be thick or thin, but however they may 
be, they should be wound in even layers with a layer of in-4 
sulating paper between layers of wire. This rule is in- 
variably followed throughout in the description of the 
windings. 

Enameled wire is favored in all secondary transformer, 
windings. In the case of the induction coils, to be described, 
the wire may be cotton covered, as these windings are sub- 
jected to wax impregnation. The induction coil secondary 
is called upon to stand enormous potentials and it is sub- 
jected to but little heat. The transformer secondary, on- 
the other hand, may become quite warm in operation anc 
it should therefore be constructed to withstand this ris 
in temperature without deterioration. In this case, the 
enameled wire is excellent for it is impervious to moderate 
degrees of heat. 

Transformer Design. — The questions : *'How many 
turns of wire do I use in the primary?'' and "What size 
should the core be?'' are familiar ones in the files of the 
author. The computation is simple and it does not involve 
any great knowledge of mathematics for its working-out. 

There are just a few basic principles to bear in mind 
before starting the calculation. The first determination 
is, of course, the capacity of the finished instrument. As 
the J4 k.w. size is a popular one, this size has been selected 
for the example. As the transformer is to be used for 



HIGH POTENTIAL TRANSFORMER 41 

charging condensers, a large magnetic leakage is desired 
and this governs the shape of the core and the method of 
placing the windings. Pligh efficiency is obtained only at 
correspondingly high cost and great weight of materials. 
In the present discussion of transformer design, the vari- 
ous computations have been reduced to the very simplest 
form possible in order that the scheme may be Avithin the 
reach of any amateur worker who knows how to use simple 
arithmetic. The subject of copper losses has been neglected 
solely because it introduces one more calculation that has 
no practical bearing upon the net results obtained. 

Let us assume, arbitrarily, that we wish a transformer 
of an efficiency approximating 93 per cent. Incidently, the 
transformer designed in this chapter is the one employed 
in the later chapter on experimental high frequency ap- 
paratus. We wish a secondary potential of 5,000 volts; a 
primary wound for 110-volt supply; and we wish to operate 
the instrument on a 60-cycle circuit. If we wish an output 
of Yi k.w. or 500 watts, and the efficiency is to be 93 per 
cent., it is obvious that we must have a greater input than 
500 watts in order to compensate for the 7 per cent. loss. 

The input is calculated by dividing the output by the 
per cent, efficiency; thus: 
500 

= 537.6344+ 

.93 
or we must have an input of 537.6344 watts in order to 
take out 500 watts. 

Core Volume. — The volume of the core receives our at- 
tention next. The initial step is to determine the w^atts 
loss in total and by subtracting 500 from 537.6344, or out- 
put from input, we find that the loss in the transformer is 
37.6344 watts. This loss is made up of the VR losses which 
are due to the heating effects in the copper of the windings, 



42 HIGH FREQUENCY APPARATUS 

and the hysteresis and eddy current losses in the core ; 
the latter are known as the core losses. The core losses 
constitute about 47 per cent, of the total of 37.6344 watts, 
or 17.688 watts. Approximately 20 per cent, of the total 
core loss will be the eddy current loss and the balance of 80 
per cent, must, therefore, constitute the hysteresis loss. To 
determine the latter loss in our core, we taken 80 per cent, 
of the core loss of 17.688 which gives us 14.1504 for the 
watts lost through hysteresis. 

Various Frequencies. — For practical purposes of the 
worker who builds the apparatus described in this book, the 
change in design necessary to adapt the various trans- 
formers for use on the various frequencies in commercial 
use, may be simplified so that when the design has been 
worked out for the 60 cycle instrument, the windings for 
25 or 125 cycles become a simple matter of proportion. The 
cores may remain the same for all frequencies. Taking 60 
cycles as the standard, the winding for 125 cycles may have 
just one-half the number of turns. The 25 cycle winding 
will have twice as many turns as the 60 cycle. In order to 
provide space for the additional turns of the 25 cycle wind- 
ing, a wire, one or two sizes smaller may have to be used 
but this is permissible in view of the intermittent work of 
the instrument. 

Proportions of -Core. — The proportions of the core call 
for some plain common sense and rule-of-thumb calcula- 
tion. One thing to bear in mind is that the core must not 
be made too long and slim as the 'reluctance is then too 
great and the primary and, consequently, the secondary 
will have an inordinate number of turns with relatively 
high copper cost. On the other hand, to make the core 
too short and thick renders the winding difficult of insula- 
tion and the coupling too close. Experience only can dem- 
onstrate the happy medium at first trial. The diagram 



Wen 



HIGH POTENTIAL TRANSFORMER 43 



en in Chapter IX shows a core of good proportions for 
his type of transformer and it may well be used as a pat- 
ern for instruments of larger or smaller size. 

Let us take the cross-section of the core at 2 inches 
quare for a trial. We must have at least 94.33 cu. in. of 
ron in all. If we make the rectangle of the core 9}i in. 
ong and 6% in. wide, outside dimensions, we shall have 
'}i + 9}i + 2% + 2}i or 25 inches of core leg. The 
■ection is 2 times 2 or 4 square inches. The length, 25, 
nultiplied by the section, 4, gives us 100 cubic inches for 
he volume of this core. As it is always well to err on the 
•ight side, this core may be taken as quite satisfactory. 
The computations for the windings which follow will show 
:hat its proportions are just right. To determine the weight 
:)f the core we multiply its volume, 100 cu. in. by .25, as 
iach cubic inch of laminated silicon steel v/eighs approxi- 
mately }i lb. This gives us 25 pounds as the weight of 
:he iron in the core. 

We may next figure the current in the secondary wind- 
ing at full load. As the potential is to be 5,000 volts, and 
the output 500 watts, we may divide secondary watts by 
secondary volts to find secondary amperes, which in this 
case will, of course, be .1 ampere. In power transformer 
work it is customary to allow at least 1000 circular mils 
of area in the conductor for each ampere of current to be 
carried. For our purposes, however, the transformer is to 
be used but a short time when it is permitted to cool and 
'in practice a density of 600 circular mils per ampere has 
been found quite satisfactory and safe. 

As the secondary current is .1 ampere, we find that our 
secondary conductor must have a area of 600 times .1 or 
60 circular mils in order that it may safely carry the cur- 
rent. In the back of the book, we find tables giving the 
area of copper wires in circular mils No. 32 is found to 



44 HIGH FREQUENCY APPARATUS 

have an area of 63.21 and this wire is accordingly quit 
suitable. 

The primary current is next in order. At a unity powe 
factor, the primar)^ watts divided by primary volts give 
primary amperes. This we find to be 537.63 -^ 110, or 4.8 
amperes. As the power factor of this type of transforme 
may be assumed to be in the vicinity of 85 per cent., \v 
shall have to compensate for this by using a somewha 
larger current value in the primary. Taking the apparen 
amperes as 4.88, we may multiply by 1.15 (assuming 
power factor of 85 per cent.) and we get 5.61, or 5.61 actuo 
amperes in the primary winding. Allowing here, also, 6C 
circular mils, we find that the primary conductor mus 
have an area of 600 times 5.61 or 3366 circular mils. Th 
wire table tells us that No. 15 has an area of 3,257 whii 
No. 14 has an area of 4,107 circular mils. Following th 
rule of plenty, we may adopt the latter as the correct con 
ductor to use for the primary. 

We now come to the point that has puzzled more am^^ 
teur experimenters than almost an}^ other, i. c, the calcula 
tion of primary turns. Of course, once this number i 
known, the determination of the secondary turns is a simpl 
matter. The formula for the primary is not complex, an^ 
its working requires only the application of ordinary arith 
metic. 

The maximum flux is equal to the density multiplie 
by the area of the core in square inches. The e.m.f. gen 
erated in the primary winding is : 

4.44 A^ Tp n 

Ep = where 

10^ 

N — maximum flux. 

Tp — prmiary turns. 

n — freauencv. 




HIGH POTENTIAL TRANSFORMER 45 

Ep — impressed primary voltage, therefore 
4 Primary voltage X 10' 

Tp^ 

4.44 XN Xn 
Working this formula, we first determine the m-aximum 
^[iux. As the section of the core is 2 inches, we square this 
^*;o get the area, or 4 inches. Multiplying the area by the 
^^'iensity per square inch, we find that 4 times 30^000 will 
'^ive us 120,000 for the maximum flux, N. The primary 
%oltage is assumed to be 110 and the equation therefore 
becomes : 
^^ 110 X 100,000,000 

== 363 + turns in the primary. 

4.44 X 120,000 X 60 
; As the turns in the secondary are found by the follow- 
"^ing formula, this calculation becomes simple : 

Es 

Tp X where 

Ep 
Es represents secondary voltage, and Ep the primary 
voltage. 

The secondary turns, assuming a secondary potential 
of 5,000, are as follows : 
5,000 

363 X -= 16,480 turns in secondary. 

110 
The space on the core for the primary and secondary 
winding is 234 in. long. Reference to the table of cotton 
covered wire shows that No. 14 D.C.C. wire winds about 
13 turns per inch. As some space is quite essential between 
winding and core, let us make the primary winding 2J4 
in. wide which will leave a space of }i in. on either side. In 
2j4 in. we can. wind 30 turns of the primary wire and, ac- 
cordingly, we shall require 12 layers in order that the re- 



46 HIGH FREQUENCY APPARATUS 

quired 360-odd turns may be placed. Wound with a few! 
thicknesses of oiled paper between layers of wire, the thick- 
ness of the primary winding from inside to outside of the 
coil or solenoid will be rather more than one inch. 

If the transformer is to be operated on 70 volts, as 
from a rotary converter, the primary will contain 70/11 
as many turns of wire. Working this we find that the 
proper number is 231 turns. For convenience, the primary 
may be made with the full quota of turns for 110 volts, with 
a tap at the 231st turn for the 70-volt connection. Like- 
wise, for 220 volts, the number of turns would have to b 
doubled and in this case the Avire would need to have bu 
half the area. This would be No. 17 wire which has ai 
area of 2,048 circular mils. For a maximum of conveni- 
ence and adaptability with a minimum of complication, the 
winding may be of 363 turns of No. 14 wure, tapped at 231 
turns, and then upon the No. 14 wire will be placed an 
additional winding of 363 turns of No. — wire with its 
starting end joined to the finishing end of the first winding. 
This primary permits the transformer to be used on 70, 
110. and 220 volts without any change other than a simple 
connection. 

The secondary turns we know to be 16,480. No. 32 
enameled wire is suitable for this winding and this wire 
winds 112 turns per inch. Suppose we make each layer of 
secondary w^ire contain 230 turns ; this will bring the width 
just over 2 inches which allows a good space for insulation 
from the core. Seventy-two layers of wire will give us 
16,560 turns which is near enough to the stipulated 16,480. 
Perhaps for the sake of having finishing and starting turns 
come on opposite sides of the winding, it may be well to 
wind but 71 layers which will give 16,230 turns. This pro- 
cedure is allowable andn indeed, preferable, as the difiference 



HIGH POTENTIAL TRANSFORMER 47 

of a hundred-odd turns in the secondary will have no ap- 
preciable effect upon results. 

The calculations for the weight of primary and second- 
ary wire are obvious. If the coils are wound upon round 
forms, as they may well be, the average length of turn is 
easily determined and multiplied by the total number of 
turns. This reduced from inches to feet gives, on compari- 
son with the wire tables, the weight of the wire in pounds. 

Induction Coils. — In places where the 110-volt lighting 
current is not available, a battery of generous proportions 
may be made to produce a high frequency current through 
the medium of an induction coil in place of the alternating 
current transformer. The coil for this work should be con- 
structed expressly for the purpose of charging condensers 
and its design is radically dift'erent from that of the con- 
ventional coil built to produce a long and stringy spark. 

While almost any coil will give some results, the 
greater effects will be shown with a coil having a compara- 
tively short and thick core and a secondary winding of 
rather coarse wire, as secondaries go. The secondary 
should be bunched near the center of the core rather than 
spread out over the entire length. The primary should be 
wound, preferably, with tw^o small wires in parallel rather 
than with one large wire. This method permits of a closer 
winding and the inside diameter of the secondary may, ac- 
cordingly, be made smaller. 

The secondary coils should be layer wound and not pie 
wound. In a large coil, from four to eight sections of layer- 
wound coils will give ample insulation as the potential is 
not nearly so high in this type of coil as is the case with 
the type built for X-Ray work. The individual sections 
may be impregnated with a mixture of equal parts of rosin 
and beeswax. 

Induction Coil Design. — The design of the coil for con- 



48 HIGH FREQUENCY APPARATUS 



1 



denser charging may be summed up in a few words. We 
cannot calculate the different parts so nicely as we did for 
the transformer and our design must of necessity be a prod- 
uct of the ''rule-of-thumb'' school ; that is, for the practical 
purposes outlined in this book. The core should take a cer- 
tain fixed proportion and this may be stated as follows : 
The length of the core to be not greater than eight times 
its diameter ; that is, a core eight inches long would be one 
inch in diameter, and so on in proportion. The number of 
turns in primary and secondary are dependent upon the 
voltage at which the coil is to be operated, the speed of the 
interrupter, etc., and, as the specifications given in this 
book are culled from practical experience, it is useless to 
attempt an explanation of the process through which this 
data was obtained. 

Kicking Coils. — The kicking coil is a simple solenoid 
of comparatively coarse wire enclosing a core of iron wires 
tightly packed. It is preferable to the induction coil, with 
its primary and secondary, for use on 110-volt direct cur- 
rent circuits where a transformer cannot be used. 

The design here is also a matter of experimental work, 
and no attempt will be made to expound the theory. Com- 
plete specifications are given in succeeding chapters on the 
construction of the various outfits in which kicking coils are 
satisfactory. 



I 



I 



CHAPTER IV. 

THE OSCILLATION CONDENSER. 

The function of the high potential condenser in a set 
of high frequency apparatus is to take the high tension cur- 
rent from the transformer or induction coil, store it up 
until the ^'condensed" energy reaches a certain critical 
value, and then discharge the current across a suitable spark 
gap, thereby setting up electrical oscillations which consti* 
tute what is called the high frequency current. In its 
simplest practical form, the condenser consists of two 
sheets of tinfoil separated by a sheet of paper. Such a con- 
denser will have a certain electrostatic capacity designated 
by the word "microfarad'' or fraction or multiple thereof. 
The single sheet of paper with its foil coatings will have a 
capacity of but a small fraction of a microfarad or mfd. as it 
is abbreviated. By placing sheets of paper and tinfoil alter- 
nately in a pile and connecting the alternate leads from the 
foil in multiple, a condenser of practically any desired ca- 
pacity may be made, the capacity increasing in direct pro- 
portion to the number of little condensers connected in 
multiple. On the other hand, if we take two identical con- 
densers and connect them in series, the pair will have but 
half the capacity of either unit. 

High Potential Condensers. — If a high tension current 
were impressed upon the simple condenser just described, 
the paper insulator or ''dielectric" would not stand the 
strain and the current would puncture the paper. There- 

49 



50 HIGH FREQUENCY APPARATUS 

fore, in order that the high voltage current may be used to 
store a large amount of energy in a condenser, the dielectric 
m.ust be made of some material possessed of exceptionally 
good insulating qualities. Glass and mica are perhaps the 
best adapted to the purpose of the amateur builder. An air 
condenser is good as is also a condenser the plates of which 
are held in a tank of oil ; these latter types are difficult and 
expensive to build, however, and they are, moreover, very 
cumbersome and heavy. 

For permanent installations, where the apparatus need 
not be moved about, a modification of the latter type is 
excellent. By building first an ordinary glass plate con- 




Fig. 11. — Single plate of glass coated on both sides with tin foil 

denser and then immersing it bodily into a tank of oil, all 
brush discharges, which represent leakage and waste, are 
eliminated. 

For most purposes of the amateur or experimenter, 
however, the simple glass plate condenser is quite satis- 
factory. Old photographic negatives of the 8 by 10 in, 
size may be had for the asking in many professional pho- 
tographers' establishments. This glass is of the finest 
quality available in the open market, and it is certainly to 
be preferred to the ordinary window glass that is frequently 
used for that purpose. 

If the 8x 10 negative glasses are coated on both sides 
with tin foil cut into 6x8 in. pieces, each plate or separate 



I 



THE OSCILLATION CONDENSER 51 

condenser will have a capacity of approximately .001 mfd. 
These plates may conveniently be grouped up into units of 
ten plates each, each unit therefore having a capacity of 
.01 mfd. By assembling any desired number of units into 
a suitable case or rack, the correct capacity for the appara- 
tus under construction will easily be provided. 

The tinfoil plates may be secured to the glass by means 
of quick-drying gold size, which is a varnish, or the foil may 
be applied after the glass has been given a very thin coat 
of beeswax applied when the glass has been heated gently 
over a flame or in an oven. In either event, it is well to 
apply the foil in a slightly larger size and trim afterwards. 
As the foil comes in sheets 6^ x 8}i in. this is easily done. 




r4i 



Fi^ 12.— -Ten plates of ,^glass built up into a unit"* with .'alternate lugs connected 

/"fien the foil has been secured on both sides of each 
piece of glass, the units may be assembled with strips of 
thin copper ribbon placed alternately projecting to right 
and left between the plates of the unit. These lugs, of 
course, provide the means of connection. The unit is then 
bound with linotape at top and bottom, the lugs folded 
around lengths of flexible lamp cord and soldered, and the 
entire unit immersed for tw^o hours in a molten compound 
of equal parts of beeswax and rosin. When this mixture 
cools, it will form a solid, non-hygroscopic seal for the unit 
of the condenser, preventing brush leakage, and excluding 



52 



HIGH FREQUENCY APPARATUS 



moisture. This procedure is to be followed in the con- 
struction of every condenser described in this work with 
the exceptions specifically noted. 

Mica Condensers. — The use of mica as the dielectric for 
the condensers of portable high frequency apparatus cannot 
be too strongly recommended. The material is light in 
weight and it is possessed of electrical properties that ren- 
der it admirably adapted to the purpose. Electrical mica 
is costly, however, and as the size of the sheets increase, 
the cost goes up in proportion ; but the price is not pro- 
hibitive if light-weight is an important consideration. The 
mica may be obtained in small sheets of almost any desired 
thickness. The method of assembly is identical with that 
of glass. 



Fig. 13. — One section of moulded condenser 

Moulded Condensers. — This type of condenser is not 
within the reach of the amateur constructor's shop equip- ^ 
ment as its manufacture requires the use of very expensive j 
dies and presses capable of exerting enormous pressure. ' 
The moulded condenser may be purchased outright, how- 
ever, in sections having a capacity of .002 mfd. each. 

The moulded condenser is mechanically strong — in- 
deed, it is practically unbreakable. The conducting mate- 
rial is of copper in sheets approximately five inches square 
and these sheets are completely sealed into a solid block of 
hard, waterproof, and practically heatproof composition 



THE OSCILLATION CONDENSER 53 

that forms also the dielectric between the plates. Such a 
condenser is ideal for the portable outfit for use on the stage 
or where great ruggedness is essential. Each section 
weighs approximately 2 lbs. and an entire condenser of 
.02 mfd. capacity would weigh but a fraction over 20 lbs. 
The outside dimensions of each unit are 6^x6^ in. while 
the thickness is about 1^ in. 



CHAPTER V. 

THE SPARK GAP. 

The function of the spark gap is to provide a c^ap be- 
tween suitable metal electrodes for the high potential cur- 
curent stored up in the condenser to leap across, thereby 
setting up the electrical oscillations. The gap, in its | 
simplest form, is a pair of zinc cylinders placed end to end 
and insulated from each other ; a means is provided where- 
by the distance between the electrodes may be adjusted to I 
the necessary point. This adjustment may be provided 
conveniently by threading the rods of zinc and supporting 
them in standards in which tapped holes have been pre- 
pared. A large knob or disc of fibre on one electrode en- 
ables the operator to make the adjustment while the current 
is passing. 

This simple gap is open to many objections when the 
higher powers are encountered, although it is quite sat- 
isfactory for use with the induction coil sets or small trans- 
former outfits. On transformers ^ k.w. or over, the 
simple gap quickly becomes heated to excess and the op- 
eration is unsatisfactory. An improvement is afforded by 
placing radiators on the electrodes to aid in the dissipation 
of the heat as it is formed. A further improvement is the 
use of larger electrodes of zinc and a step still further is 
taken if the electrodes are made of nickel-steel ; owing tQ 
the difficulty of work this substance, however, it is not 
considered within the reach of the experimenter. It is 



54 



THE SPARK GAP 



55 



sometimes possible to obtain the nickel-steel rod in suit- 
able lengths, however, and, in this event, it should most 
certainly be employed. 

If an air blast is directed against the electrodes and 
into the gap, the ' operation will be improved materially. 
The current of air serves not only to cool the electrodes 
but to wipe out any arc that may tend to form. 

The Rotary Gap. — In this type of gap, one electrode 
is stationary while the other rotates past it a certain num- 
ber of times per second. The various modifications of this 
simple rotary gap are bewildering to contemplate and no 
attempt will be made to describe all of them. Suffice it 
to say that the rotating member may consist of a single 



TiwiJ n flpMa iliO ;j^1 U:.^ 



Fig. 14. — Designs of stationary spark gaps. The type at the right is fitted with 
rotating discs to dissipate the heat generated by the spark 

disc of metal from the periphery of which pieces have been 
cut to form teeth ; or it may be a disc of metal with me- 
tallic studs fastened to it to form the rotating electrodes ; 
or it may be a disc of insulating material with metal studs 
passing enirely through it near the periphery; in the last 
instance, the stationary electrode will be in duplicate, with 
one on either side of the revolving disc. 

The advantages of the many types are mechanical 
rather than electrical. The builder, in selecting a certain 
type, will have to consider the limitations of his shop equip- 
ment. One is about as good as the other so far as results 
are concerned, and almost any rotary gap is better than 
even a good one of the stationary form. 



56 



HIGH FREQUENCY APPARATUS 



The number of studs or sparking points required will 
depend upon the diameter of the rotor disc and the speed 
at which it is to be driven. The number of studs and the 
speed govern the tone or pitch of the note imparted to the 
spark. With 12 points and a motor running at 1,800 R.P.M. 
the tone of the spark is musical and pleasant to the ear ; 
this is in striking contrast to the crackling or crashing 
spark of the stationary gap. While this feature is of 
greater importance in the case of radio telegraph apparatus 
than with demonstration coils, still the pleasing musical 
hote makes a good impression upon the audience. 

The distance between the rotating and the stationary 





Fig. 15. — Simple rotary gap 

electrode should, in general, be as short as possible with- 
out striking. The gap should certainly be adjustable by 
small degrees and the adjusting mechanism should prefer- 
ably employ a screw with an insulated knob in order that 
the spark gap may be varied while the current is passing. 
The Quenched Gap. — By making the spark gap elec- 
trodes very massive, facing them off very accurately in a 
lathe, providing large radiation surface on each electrode, 
and, finally, by supporting the electrodes in such manner 
that the separation of their faces is but a few thousandths 
or perhaps hundredths of an inch, we have what is com- 
monly termed the quenched gap. The large mass of metal 



THE SPARK GAP 



57 



and its radiation surface tends to dissipate the heat as fast 
as it is produced and the condenser discharge takes the 
form of a series of very short, clean, and nearly undamped 
surges. The large surface and the short gap increase the 
total number of discharges per alternation of the current 
from one or two per alternation to several hundred or per- 
haps a thousand. This does not means that the frequency 
(f the current is affected by the quenched gap character- 
istics just mentioned. The frequency of the oscillations 
may be just as high in the ordinary gap but the groups 
or trains of oscillations, or perhaps we had better say the 




Fig. 16.- Sitnple form of quenched gap 



groups of condenser discharges, may occur many more 
times per second, or per alternation of the current, in the 
quenched gap. That is to say, the condenser becomes 
charged and discharged many more times per second, while 
the frequency of the oscillations in each separate discharge 
may remain fixed. 

The advantages of the quenched gap are manifold while 
the difficulties identified with its construction and use are 
almost as num^erous. The quenched gap requires good 
tools and good w^orkmanship. In operations, it is likely 
to become overheated and its operation will then be un- 



58 HIGH FREQUENCY APPARATUS 

steady. It is heavy as compared with the ordinary gap 
and it is costly. 

To counterbalance the disadvantages enumerated, w^e 
may say that the results obtained from this form of gap 
are remarkable. The high frequency discharge from a 
Tesla or Oudin coil operated with it is astonishing; in 
stead of the thin, wiry discharge or spark, we get a flaming, 
white discharge that can best be compared with the flame 
from a very high potential, low frequency transformer 
The high frequency discharge is not silent, however, but 
it partakes of a loud, crashing hiss. For electro-therapeutic 
work, the quenched gap is splendid, providing it is properly 
designed, built, and cared for. The X-Ray current is par- 
ticularly energetic and for auto-condensation, where a high 
discharge rate is imperative, the milli-amperage may reach 
1400 without great discomfort to the patient. So, the 
reader will see that even with all of its many troublesome 
features, the quenched gap is well worth building, if for 
purposes of experiment only. 

The Rotary Quenched Gap. — For radio telegraphy, a 
high pitched note is highly desirable as this spark can be 
distinguished from the atmospheric crashes and other ex 
traneous sounds so often heard in the telephones of a 
radio receiver. The ordinary rotary gap gives this note and 
works well. The 500-cycle alternating current sent into 
a special transformer and used to discharge across af 
quenched gap works even better but the 500-cycle cur- 
rent is a thing not to be attained by the average experi- 
menter. Along came a chap a few years ago with a com- 
bination of quenched and rotary gap that threatened to dis- 
place the 500-cycle sets for, by means of his transmitter, 
the ordinary 60-cycle current could be sent into the ap- 
paratus and be made to produce a clear-cut musical note 



THE SPARK GAP 59 

with every possible advantag-e of the quenched gap and 
;vith many additional advantages as well. 

In the rotary quenched gap, the rotating electrode 
takes the form of a large copper disc having radial slots 
milled across its surface and thus leaving w^edge-shaped 
members of copper protruding for the sparking surface. 
The stationary electrodes were two in number, each form- 
ing a semi-circular piece of copper with radial slots and 
projections to correspond with the rotary member. The 
latter was placed upon a shaft and mounted in suitable 
bearings so that it could be held with its face but a few 
thousandths of an inch from the stationary members, and 
rotated at a high rate of speed. Here we have the true 
quenched gap, subdivided into a series of discharge points 
which, when the disc was rotated, split the condenser dis- 
charges into groups which were clearly defined and which 
imparted the beautiful musical tone to the spark. 



CHAPTER VI. 

OSCILLATION TRANSFORMERS. 

The function of the oscillation transformer is to take 
the oscillatory current set up by the discharge of the con- 
denser across the spark gap, and increase it from a poten- 
tial of a few thousand volts to practically any desired po- 
tential. While the principle is exactly the same as that 
involved in the ordinary low frequency transformer, the 
high frequency type is possessed of a few characteristics 
peculiarly its own. For instance, the primary w^inding of 
the oscillation transformer may have from one to ten turns 
of very thick copper conductor in it ; in this short and very 
low resistance winding, current oscillates at a potential 
of several thousand volts. The secondary of the oscil- 
lation transformer may contain but a single layer of wire, 
with a total number of turns running into hundreds 
instead of thousands or tens of thousands as is the case 
with the low frequency type ; but in this short secondary, 
with its few turns, may be induced an immeasurably great 
potential — a voltage running into the millions. The third, 
and perhaps the greatest, distinguishing feature of the os- 
cillation transformer is the fact that it has no iron core ; the 
presen.ce of any iron whatever is detrimental to the action 
of the device. 

Various Types. — Considerations of voltage, current, 
weight, frequency, and the various factors of this nature 
enter into the design of the oscillation transformer. The 
windings may be insulated by air space, oil, wax, or pe- 

60 



I 



OSCILLATION TRANSFORMERS 



61 



trolatum. The primary may be an open helix of bare cop- 
per bar, strip, ribbon, or tubing, or it may consist of a coil 
of heavily insulated cable. The secondary may be wound 
in a single layer upon a cardboard or wooden cylinder, or 
upon a wooden cage, or it may be wound in a series of nar- 
row layers on insulating paper or cloth. The secondary 
may also be in the shape of a cone or a flat spiral resemb- 
ling a spider web. 

Oudin and Tesla Types. — Oscillation transformers may 
be broadly classed under these two headings. The Oudin 




Fig. 17. — Wiring diagram for Oudin coil 

coil is in reality an auto transformer, /. r., its primary and 
. secondary are connected together at a neutral point which, 
in the case of high frequency apparatus, should be 
grounded. In the Tesla coil, the only connection between 
, the primary and the secondary is an inductive one; the two 
I windings are separate and distinct. (See Fig. 18.) 
I The third type that should be mentioned, as it is per- 

haps the most practical of all, is a combination of the Tesla 
and Oudin circuits. This consists of two Oudin resonators 
* placed side by side and having their ground connections 



62 



HIGH FREQUENCY APPARATUS 



joined with a cable which places the two primaries in 
series. The oscillation circuit is, of course, through both 
primaries. Still a further modification of this circuit is 
made by placing the two resonators base to base as shown 
in Fig. 20. This makes virtually a Tesla coil of the pair, 
the only distinction being in the grounded neutral point. 

Advantages of Various Types. — The Tesla coil gives 
the longest spark between points of any of the various 
types. This coil is difficult of construction, however, and in 
mechanical design it is fundamentally poor. The greatest 




Fig. 18. — Wiring diagram for Tesla coil showing transformer, spark gap and 

condenser 

problem is to support the primary and secondary and still 
prevent leakage of the current. The combined type, Fig. 
20, or the style shown in Fig. 19, will overcome this diffi- 
culty with but a slight loss in results obtained. 

The Oudin coil gives an enormous brush discharge 
from its single terminal. In a large coil, the streamers of 
purplish fire dart out like the branches of a tree to a dis- 
tance of several feet in all directions. Such a coil, properly 
proportioned and carefully built will give splendid results 



ii 



OSCILLATION TRANSFORMERS 



63 



The construction is simple and the design strong both elec- 
trically and mechanically. For portable purposes, the 
Oudin coil is the ideal type to use, particularly if it is de- 
sired to keep down weight and bulk and to have apparatus 
that will stand the hard knocks of road work. 

Proportions of Coils. — In the actual construction and 

subsequent use of some dozens of different types of high 

frequency coils, the author has evolved a few simple rules, 

which, for som.e inexplicable reason, appear to give the 




Fig. 19. — Two Oudin resonators placed side by side to produce very long sparks 

pass-word to the realm of successful coil building. While 
there is a perfectly good method by means of which these 
coils may be designed ''on paper,'' through the medium of 
various formulae, all more or less complex, the average 
practical worker in this field will admit that the time-worn 
"rule of thumb" method is possessed of certain advantages 
in this case as in others, particularly when the results of 
"rule of thumb" calculation are carefully noted and the 
mediocre designs eliminated from future consideration. 

With this brief explanation or, perhaps, apology, for 



64 



HIGH FREQUENCY APPARATUS 



the use of the much used — and abused — rule of thumb, 
we may proceed to look into the actual design of oscilla- 
tion transformers of various sizes and for various pur- 
poses. Without attempting any explanation of the reasons ^ 
therefor, the author may state that, in his experience, the 
secondary of the Tesla coil should be wound upon a cylinder 
the length of which is three times its diameter. The Oudin 
resonator secondary should be wound upon a cylinder hav- 
ing a length slightly less than twice its diameter. Apply- 
ing this simple rule, a Tesla coil with a secondary 12 in. 
in diameter, would be 36 in. long. The Oudin coil would 




Fig. 20. — Two Oudin resonators placed Jjase to base 

be about 22 to 24 inches high if its diameter were 12 ins. 
This rule applies only in the case of truly cylindrical sec- 
ondaries. 

The number of turns of wire on cylindrical Tesla coil 
secondaries should be in the proximity of 800, while the 
Oudin secondaries may contain from 400 to 600 turns for 
long sparks and from 100 to 300 for shorter and heavier 
discharges. This rule has been found to follow in the case 
of either large or small coils and the figures given have 
been taken from charts giving the effective windings for 
a great many coils. 






OSCILLATION TRANSFORMERS 



65 



The cone-shaped coils are particularly effective as they 
are theoretically correct in design. The proportions for 
cones may vary from a perpendicular equal to the diameter 
of base to a perpendicular 1.5 times diameter of base. The 
latter is better for long sparks. The windings of cones 
should contain from 100 to 500 turns of wire for short and 
thick, or long and comparatively thin sparks, respectively. 

For the very closely coupled coils such as the pancake 
form, where the winding is in layers, and the coil sealed " 
in, the number of turns may run up as high as 1500 to 2000 





Fig. 21. — Showing proportions for Tesla and Oudin secondaries of any desired size 

turns. The coil is of comparatively small diameter in this 
event. The layers of wire should never be very wide as 
the insulation will not hold up. 

The conductor for the secondary windings of all types 
of oscillation transformers should be of soft, pure copper 
wire. The insulation may be of cotton or silk but not of 
enamel. The use of the latter for high frequenc}^ secon- 
daries has given the author great disappointment in the 
construction of several large and comparatively expensive 
coils. The insulation on the wire is of no value whatever 
except to provide a mechanical separation for the turns 



66 



HIGH FREQUENCY APPARATUS 



of wire and to form a base or support for whatever in- 
sulating substance is applied to the wire subsequently. 

Secondary Insulation. — One fact stands out promi- 
nently after the worker has built and experimented with a 
few coils. No solid insulation of any kind is of the slight- 
est avail when working with high frequencies and very high 
potentials ; glass, hard rubber, mica, empire cloth, and even 
paraffin wax seem actually to help the current to pass. 
'The terminals of a coal may be separated beyond sparking 
distance in air and when a piece of heavy plate glass is 





i 



Fig. 22. — Proportions for cone-shaped secondaries of any size 



interposed, the discharge immediately starts to wind its 
way over the surface of the glass, finally piercing the plate 
as if it were of cardboard. Therefore, let the uninitiated 
worker bear this fact in mind : That to attempt the insula- 
tion of the Tesla primary from the secondary by means of 
any of the old reliables in the case of the ordinary induc- 
tion coil, is the height of folly in the case of the high fre- 
quency coil. Liquid oil, freed from all moisture, is the 
very best insulator for these high frequency currents. It 
is heavy and sloppy to handle, however, and its use pre- 
cludes the possibility of obtaining the beautiful brush ef- 



OSCILLATION TRANSFORMERS 67 

fects from the secondary in the air. Next to oil- comes a 
mixture of beeswax and rosin in equal parts. This seems 
to be practically the only solid, or nearly solid, insulating 
substance that will stand up under the strain. Last of all 
comes air. We say last because the air insulation must 
be greater in extent than either of the predecessors; but 
notwithstanding this fact, the air insulation is the one 
cheap, light-weight, and absolutely reliable insulation that 
the high frequency worker has at his command. A separa- 
tion of a few inches more, perhaps, between primary and 
secondary, but a mechanically and electrically good con- 
struction, and, what is more, accessibility of all of the parts 
at an instant's notice, is the significant list of advantages 
possessed by this insulating medium. 

On air-insulated coils, the secondaries should be wound 
with a space between each turn and its neighbors. This 
space will depend upon the potential to be set up at the 
top of the coil and ordinarily the separation should be about 
the width of the wire itself. Bare wire may be used but 
it is not recommended. Double cotton covered wire has 
been the choice of the author after many experiments to 
determine the relative merits of all known coverings. The 
double cotton covering forms an excellent base to soak 
up shellac which, when applied in a half-a-dozen coats, and 
thoroughly dried out, has been found to seal up the turns on 
the open cylinder, preventing in large measure, the leakage 
between the turns when the coil is operating at full power. 
Theoretically the winding of the secondary should start 
with turns close together at the base, the separation grad- 
ually widening out as the top or high potential end of the 
coil is reached. This method of winding is impracticable 
for the average amateur constructor, however, and he must 
needs resort to the next best expedient of making all turns 
sufficiently separated to take care of the potential. 



68 



HIGH FREQUENCY APPARATUS 



Oil and Wax Insulations. — The oil insulated coil may 
be very closely coupled; that is, the primary may be but 
slightly separated from the secondary. The case or con- 
tainer for the coils may be of wood, lined with zinc. The 
cover, of course, must be of some good insulating material 
such as glass, hard rubber or marble. Slate should not be 
used as the minute metallic veins found in some varieties 
will be ruinous to the output of the coil. The high poten- 
tial leads from both primary and secondary may be brought 
up through porcelain, glass, or hard rubber insulators at- 
tached to the top of the case and extending down into the 
oil. 



m 










m- 


■ 






i 


E :::: : 


l-a 


. 




1 


wm 








— Space turns 





Fig. 23. — The turns^ of wire in the secondary should be spaced to provide adequate 
insulation for .the extremely high potential 



The compound of equal parts of beeswax and rosin pre- 
viously mentioned is used to seal in the pancake coils of 
portable electro-therapeutic outfits where every eflfort must 
be expended in the direction of light weight and compact- 
ness. This compound is melted up in a double boiler, as 
the insulating properties are ruined if the mixture is per- 
mitted to scorch. The pancake coil, which is specifically 
described later in this book, is immersed in the hot com- 
pound and permitted to remain for hours until the windings 
and the paper separating layers are thoroughly impregnated 
with the molten wax. 

The advantages of the close coupling of primary and 



i 



OSCILLATION TRANSFORMERS 69 

secondary made possible through the use of some better 
insulator than air are found in the greater efficiency of the 
oscillation transformer constructed in this way. The spark 
is thicker and hotter, as well as being of the desired length. 
' This quality is to be desired in X-Ray work in particular. 
For demonstration apparatus, however, the builder can do 
no better than use the air insulated coils. 

Constructional Features. — The simplest Tesla or Oudin 
coil to make is that in which the secondary is a cylinder 
of cardboard such as a large mailing tube, or a tuning coil 
cylinder, wound with a few hundred turns of insulated mag- 
net wire. The primary may consist of a few turns of cop- 
per ribbon wound into a spiral with the turns separated by 
a strip of corrugated board such as is used for packing 
purposes, the whole being secured with tape at four or five 
points on the spiral. 

From this simple start, larger coils may be developed 
along similar lines. Cardboard cylinders may be purchased 
in sizes as large as 8 x 13 in. and larger ones may be made 
to order. Very large cylinders should be made of w^ooden 
slats pegged with wooden pegs to wooden discs of the de- 
sired diameter. 

Primaries may be of almost any heavy conductor avail- 
able. As the tendency of the high frequency current is to 
travel upon the surface of the conductor, it is highly desir- 
able that the primary be made either of flat ribbon or strip 
copper, or else of copper tubing of relatively large diameter. 
Stranded conductor is excellent and if the precise number 
of turns is known and no tuning necessary, the builder may 
use heavy stranded cable with excellent results. 

The ideal primary conductor is copper strip or bar, 
would edgewise into an open helix. Such a primary may 
be made compact and mechanically strong and it is splendid 
from the electrical standpoint. This conductor permits of 



70 HIGH FREQUENCY APPARATUS 

closer coupling without danger of sparking from secondary 
to primary. The edgewise wound strip is difficult to make 
as the reader may well imagine. The mechanical problem 
involved is a real one and for the few turns the average 
worker will require, to construct a winding rig would be- 
out of the question. The strip can be purchased ready 
wound, however, in three convenient sizes, and its use is 
specified in the construction of several coils in this work. 



CHAPTER VII. 

INDUCTION COIL OUTFITS FOR BATTERY 
CURRENT 

Of all the experimental apparatus within the reach of 
the amateur builder, none can compare with the high po- 
tential, high frequency transformer when it comes to a 
question of demonstration or entertainment. A simple 
card-board cylinder, wound with a few hundred turns of 
magnet wire in one layer, set on the top of the helix of his 
wireless set will give the experimenter a spark several 
inches long. This spark he can play with to his heart's 
content for it is perfectly harmless. Taken through a piece 
of metal held in the hand, the current produces no shock 
whatever even though the voltage may be expressed in the 
thousands. This is explained by the fact that the current 
changes its direction of flow so rapidly that the nerves can- 
not transmit the sensation of pain and the muscles cannot 
respond to the pulsations. 

Induction Coil Apparatus. — The experimenter who 
numbers among his possessions a spark coil suitable for 
radio telegraphy, may delve into the mysteries of high 
potentials, and high frequencies without spending any great 
amount of money for the extra apparatus needed. If he 
has the coil, he will most likely have also a spark gap and 
3 high tension condenser. 

With this equipment to start off with, the experimenter 
will have only to add a simple Gudin resonator to his outfit 
in order that he may play with the sparks for the entertain- 

71 



72 



HIGH FREQUENCY APPARATUS 



ment of his friends and himself. The resonator can De^ 
built by any worker who has made a tuning coil. A card- 
board cylinder from 2 to 4 in. in diameter and twice its di- 
ameter in length may be fitted with the usual wooden heads 
and given a coat of shellac. When the latter is quite dry, 
the cylinder may be mounted between centers in a simple 
winding rig such as is shown in the illustration. The cyl- 
inder, turned away from the operator by hand, is then to 
be wound full of double cotton covered wire which may be 
of any size between 34 and 28 B. & S. gauge. 

The completed secondary is then to be coated with 
several applications of shellac, each layer being permitted 



jT' Wooden Head in either End of Cy finder.. ^^ 



rxJ- 



lengfh of Cardboard Cylinder 
h be aboui twice its Diameter 




Fig. 24. — Cardboard cylinder 



and wooden heads 
transformer 



for secondary of oscillation 



to dry thoroughly before the next is applied. When the 
final coat is hard, the secondary may be mounted upon a 
simple wooden base by means of screws passing up from 
beneath and into the lower wooden head. The lower end 
of the winding is carried down through the base to a ter- 
minal which will be ''ground.'* The upper end of the wind- 
ing terminates in a rod carrying a brass ball at its tip. 
This ball and rod may be taken from the clapper of an old 
electric bell, or, the ball may be a large leaden shot of the 
variety known as ''buck shot." 

The primary is composed of twelve turns of very heavy 
copper wire such as is used for the transmitting helix in a 



I 



I 



INDUCTION COIL OUTFITS 



n 



wireless set. The wire is wound upon dowel rods set up 
in the base surrounding the secondary coil. The rods 
should be so placed that the inside diameter of the primary 
winding is 1^ times the diameter of the secondary. The 
winding of heavy wire should cover Yz of the height of the 
secondary cylinder. If the induction coil used to excite 
this oscillation transformer is of large size, the secondary 
may send sparks into the primary. In this case, the pri- 
mary must be made larger in diameter. The directions 
here have been for a comparatively close-coupled coil as 



This ftrid 
fast on 
spi ndle 



jr 




IVind thread and wir« 
in parallel. Remove 
thread when winding 
i3 complete. 



This end free 
on center 



Fig. 25. — Apparatus for winding secondary of oscillation transformer 

that type will give maximum results with the usual wireless 
spark coil. 

The lowest tura of the primary helix is to be connected 
with the ground terminal to which the lower end of the 
secondary winding is attached. The wiring diagram is 
given in Fig. 27, and the reader will notice that the spark 
gap is connected across the secondary of the spark coil ; the 
condenser and primary of the resonator are in series across 
the spark gap. A\^hen operating the coil, try A^arious ca- 
pacities of the condenser, a variation of the turns of the 



74 



HIGH FREQUENCY APPARATUS 



primary, closing up or opening the spark gap, etc. A few 
trials will bring the circuits into resonance and the ball at 
the top of the resonator will give out beautiful streamers 
of purplish fire. If a piece of metal is held in the hand 
and approached to the ball, a spark several inches long 
will jump into the metal without the operator feeling the 
slightest sensation of shock. 



Discharge ball 



tscinaii&n transfonnef 





■ Ground Induction Cofl 

Dle^raa cT cca'^ootlons 



Prinary 12 turns of 
heaTy copper or braB*. 
wire. 



For induction coil 
sets, primary to b8 
I5 times diameter 
of secondary drute« 



Figs. 26 and 27. — Data for small Oudin resonator and diagram connections ■ 

Induction 'Coil Construction. — In the event that the ex- 
perimenter is not the possessor of an induction coil giving 
a fat, hot spark, he will need either to buy one outright or 
else construct one in his home workshop. The latter 
course is permissible if he is a fairly careful and patient 
mechanic. 

The data given in this chapter is for the construction 
of a coil built expressly for radio and high frequency work 



IXDUCTIOX COIL OUTFITS 



n 



and It IS totally different in windings and proportions from 
the ordinary spark coil that is intended primarily to give a 
- long spark. The coil to be described is not rated in spark 
^ length but in watts capacity. Through the use of a suit- 
able interrupter, this coil may be operated at 10 volts and 
10 amperes continuously. The secondary winding is of 
comparatively low resistance, thus it is well adapted to the 
purpose of charging condensers. 

Core and Primary. — The core of this coil is a bundle 
of soft iron wires tightly compressed into a cylinder 12 in. 
long and 1^ in. in diameter. The core w^ire can be pur- 
jchased ready cut and perfectly straight so that its formation 
into a cylinder is a simple matter. Given the necessary 



.r 



, . Binding wires . 



Tape binding 
\r started 



Core a bundle of Iron wires 



'IZ'- 




Fig. 28. — Core with tape binding started 

amount of straight iron w^ires, the builder grasps the bundle 
The silk is tough and strong and the worker will be enabled 
to preserve the solidity of his bundle as he removes the 
binding wire sand replaces them w^ith the silk wrappings 
with both hands and w^ith a twisting motion forms the wire 
into a compact cylinder. A piece of wire is then wound 
around the middle of the core and twisted. Another is 
added at each end. The twisting operation is then con- 
tinued, taking up the slack in the binding wires by twisting 
the ends with a pair of pliers. Soon the bundle will be per- 
fectly straight and hard. 

Starting at one end, the binding wires may be removed 
and a winding of silk ribbon started spirally over the core. 



16 



HIGH FREQUENCY APPARATUS 



When the entire core is covered, the final turn of ribbon! 
may be held with shellac and a few turns of thread taken 
over the end to insure permanency. The whole core, with 
its wrapping of ribbon, is then to be suspended in a trough 
filled with thin shellac. A submersion of an hour will have 
served largely to fill the interstices between wires and to 
soak the ribbon thoroughly. The core is then hung up to 
drain and dry. The latter operation will take the best part 
of 24 hours. When the shellac is hard, the core will be 
almost as solid as if it were of one piece of iron, and it is 
then ready for w^inding. 

The primary is in two layers. The end of a spool of 
No. 14 D.C.C. magnet wire is placed under a loop of the 



Ifioanlld coToring 



Primary vindlne 




End of winding held under tape 



Fig. 29. — Core and primary, showing how finishing end of primary winding is held 

under a loop of tape 

silk ribbon on the core and the winding started by turning 
the core with both hands. The second turn of wire grips 
the ribbon loop and thus secures the starting turn. The 
first turn should start at a distance of one inch from the 
end of the core and the first layer ends at this distance from 
the other end. The second layer of wire is wound upon 
the first, with a layer of empire cloth between. The fin- 
ishing end of the primary winding is secured with a loop of 
ribbon, the ends of the "loop being pulled tight after the 
ribbon has been covered by the last three or four turns oft 
the winding. The entire primary is then to be wound with 



INDUCTION COIL OUTFITS 11 

silk ribbon in exactly the same manner as the core and 
the end where the leads come out should be wound with a 
number of turns of strong thread to prevent the possibility 
of the starting and finishing turns coming loose. The en- 
tire core and primary is now to be immersed in a compound 
of equal parts of beeswax and rosin, melted in a double 
boiler to prevent scorching. An immersion of an hour or 
two will suffice when the coil may be removed to drain and 
cool. 

Insulation. — When the primary has cooled, it may be 
covered with four layers of micanite sheeting. This s;^.b- 
stance is built-up mica made into a flexible sheeting about 
iV in. thick. Very thick shellac is liberally applied as the 
wrapping proceeds and when the final turn of the micanite 
is taken over the primary, the whole cylinder should be 
temporarily wrapped with tape until the shellac dries out 
thoroughly. When this is at last accomplished, the struc- 
ture is to be placed in an oven until slightly warm, after 
which it is stood on end with the lower opening filled and 
the beeswax-rosin compound poured into the space between 
primary and insulating tube. The length of the latter is 10 
in. and an inch of core is therefore left projecting at either 
end to permit of mounting in the frame to be described. 

Secondary Winding. — The secondary is wound in four 
sections, each section being wound in layers upon oiled 
paper X^A in. wide. The wire is No. Z2 S.C.C. Each 
layer contains 112 turns of wire and the width of the layer 
of wire is 1 in. ; therefore, there is a margin of J4 i^^- on 
cither side of the layer of wire. Each section is wound 
in 61 layers and the total turns to each section is accord- 
ingly 6832. The four sections will comprise 27,328 turns 
in consequence. 

The secondary sections may be wound either in a lathe 
or else upon a form mounted in a simple winding rig such 



78 



HIGH FREQUENCY APPARATUS 



as the illustration suggests. The outside diameter of the 
micanite insulating tube over the primary will be approxi- 
mately 2%. in. and this shall therefore be the internal diJ 
ameter of the sections. The form consists of a disc of woo* 
nailed to one end of a short cylinder of wood and the whole 
mounted either in the lathe or in bearing supports a 
shown. The cylinder should be 2^4 i^- in diameter an 
about 2 in. long. 

In starting the winding of a section, the wooden cylin' 
der should be covered with a layer of cord to make possible 



le 

1 



Turn in this 
direction 



(t 



] 1 



VTooden disc attache^, 
to cylinder 



t> 



This position 
for sectiona 
#1 and 3 



Revers* 
for #2 
and 4 



Fftaten securely to bench 




Fig. 30. — Winding apparatus for secondary sections 

the removal of the section. The first layer of oiled paper 
may be wound upon the cord which is pulled out after the 
section is finished. In the first paper layer there should 
be six or eight thicknesses of the oiled paper to make a 
mechanically strong support for the winding. The starting 
end of the No. 32 S.C.C. wire is soldered to a piece of 
thin copper ribbon inserted between layers of paper, and 
the first layer of w4re wound until 112 turns have been 
placed. At this juncture the winding should be an inch 
wide. A layer of oiled paper is then taken over the wire 



IXDUCTIOX COIL OUTFITS 



79 



and the second layer of winding placed. This is continued 
until 61 layers have been wound. The finishing turn of 
the wire is soldered to a piece of copper ribbon and ten 
layers of paper taken over the wire. The ribbon passes 
between the eighth and ninth layers of paper which hold it 
securely. This completes a section which is now to be im- 
pregnated with the beeswax-rosin compound. 

In winding the first section, the builder is to turn the 
lathe away from him and have the disc-end of the cylinder 
at his left. The winding is to start at the left hand end of 
the cylinder next to the disc. This procedure is also to 







// 3" 








r'n 












" f- 






1 


/^ 




\ 




:: ■ • 1: 


jn nj- 


■•» 







7' 

e 


^Clearance hole for 10-32^'^ 
Hole for core^,^^ 

Counterbore ^t* 


— 














ni- 






\ — 


Clear ^4 


■ 














J' 






<s- 


1 




Side elevation of frame 






End elevation 







Fig. 31. — Details of the frame work 

be followed with one more section. When these two sec- 
tions are wound they should be numbered 1 and 3. The 
winding rig is then to be reversed so that the disc-end of 
the cylinder is at the right. Starting the winding next to 
the disc as before and turning in the same direction, /. r., 
aw^ay from the operator, the section under construction will 
be wound in the opposite direction from the two predeces- 
sors. This section is to be numbered 2 and its companion. 
No. 4, is wound in the same way. The reason for this will 
be seen when the assembly starts. 



80 HIGH FREQUENCY APPARATUS 

Assembly. — The frame of the coil is well shown in Fig, 
32. The ends of the core fit into holes into upright pieces 
of wood which form the supports for the entire coil. The 
secondary sections are arranged upon the micanite tube in 
the order of their numbers, starting from left to right. If 
the winding has. been done as described, the first outside 
lead will go to the binding post, S^, the inside lead of sec- 
tion 1 to that of section 2; the outside lead of section 2 to 
the outside lead of section 3 ; the inside of 3 to the inside 
of 4; and the outside of 4 to the remaining binding post. 
The two primary leads are carried to one binding post 
in the base and to one side of the interrupter respectively. 

Interrupter and Condenser. — An independent interrup- 
ter is much to be preferred for use in connection with this 
coil. The interrupter may be of the mercury-turbine type, 
the vibrating contact type, or the electrolytic. The last 
mentioned style of break will give the greatest results if 
the interrupter is properly designed and built ; if the worker 
does not care to go to the trouble of making this rather 
delicate device, the construction of which involves some 
rather good glass-working, he may purchase the interrupter 
outright for $2.25. This price would scarcely cover the 
cost of the materials and the workmanship on the break 
if the amateur worker were to build one. 

The vibrating type of break will give good results if its 
contacts are of generous proportions and the component 
part of the interrupter properly designed. The data given 
herewith specifies the use of hard silver contacts -^q in. in 
diameter rather than platinum ones of a much smaller size. 
Before we proceed with the description of the vibrating in- 
terrupter, however, a brief mention may be made of the 
mercury-turbine break, which is in many ways the ideal i 
type. ' 

In the mercury-turbine break, a stream of mercury is 



INDUCTION COIL OUTFITS 81 

raised through the medium of a pump and projected in a 
fine stream against a series of metallic vanes with which it 
makes successive contacts. This device is even more diffi- 
cult of construction than any of the other types and no at- 
tempt will therefore be made to describe it in detail. The 
mercury-turbine interrupter costs in the proximity of $9.00 
and it requires a small electric motor for its operation. It 
may be used on practically any voltage from six to 110. 

The relation of the vibrating interrupter to the rest 
of the coil is shown in Fig. 32, while the details of the in- 
terrupter are given in Fig. 10. Using the reference num- 
bers in the drawing, 5 is a spring of phosphor bronze, 3^ 
in. long, 1 in. wide and approximately 1/32 in. thick. To 
' the end of this spring is secured the armature, 6, of soft 
i iron, by means of four small screws. This armature may 
be turned from ^ in. soft iron bar or it may be cut from 
the end of a 1 in. rod of the same material. The contact, 7, 
is cut from a piece of -^q in. silver rod, drilled and tapped 
, for the small screw that secures it to the spring in the posi- 
I tion show^n. The stationary contact, 8, is made of the same 
material and it is carried on the end of the 14-20 milled- 
head «crew, 9, which is threaded into the stud of silver. 
The adjusting screw, 9, is carried by a cross arm of heavy 
brass bar, 10, which, in turn, is supported by pillars of 
brass, 11, at either end. The vibrating spring, 5, is sup- 
ported at its lower end upon a bar of brass, 12, to which it 
is secured with screws passing through a washer plate. 
This construction is essential in order that the spring may 
have a definite point or edge from which to vibrate. 

The condenser to be shunted across the interrupter 
should be adjustable. The builder is strongly advised to 
purchase this condenser outright. The task of making up a 
condenser of tinfoil and paraffined paper is a discouraeir*^ 
one and the manufactured article can be purchased so 



82 



HIGH FREQUENCY APPARATUS 



meCT 



^ 


^ 








>^— ^ 









i;: 


® 




(D 


>C— X 








y 







a^ 



5iS 



n^ J^l 



■rf=: 



--^^ 



Py 



© 



® 



© 



w 



mJc: 







INDUCTION COIL OUTFITS 



83 



cheaply that the amateur builder is not justified in making 
one. The standard telephone condenser of 1 mfd. capacity 
is approximately correct in capacity and if four more sec- 
tions of .5 mfd. each are added, the necessary range of ad- 
justment is obtained. 



r 




M? 



Side elevation 



Front elevation 



Fig. 33. — Details of the interrupter 

I If the builder wishes to make his own condenser, he 

I may purchase 250 sheets of heavy paraffined paper such 
j as is used to wrap candies in. This paper may be cut to 
form 500 sheets of paper 8 x 10 in. in size. The tinfoil 
, should be thin in order that cost and weio'ht may not be in- 



84 



HIGH FREQUENCY APPARATUS 



ordinate and it is to be cut into 6 x8 in. pieces. These tin- 
foil sheets, with strips laid on alternately for lugs, are 
placed between the waxed paper sheets in piles of 100 sheets 
each. The condenser will therefore comprise five units of 
100 sheets to the unit. The specifications given are for a 
condenser of large proportions, but in the author's experi- 
ence, the average amateur builder is not equipped with the 
presses necessary to compress the units to the extent where 
their capacity is large for a given size of sheet. The only^ 
device of this kind that is within the reach of the experi- 




Fig. 34. — Diagram of connections for the induction coil 

menter is a letter press and this implement gives but a 
small fraction of the pressure used by the manufacturer 
of the standard condenser. 

The diagrams of connections is given in Fig. 34. The 
disposition of the connecting wires is not given in the draw- 
ing of the completed coil, Fig. 32, for the simple reason tha 
the extra lines would tend to confuse and the builder whc 
is capable of turning out this coil will certainly be able to 
place his connecting wires in a workmanlike manner. 






INDUCTION COIL OUTFITS 85 



High Tension Condensers. — The condenser for con- 
nection across the secondary of the induction coil may be 
made by coating both sides of an 8 x 10 photographic nega- 
tive with tinfoil in sheets 6x8 in. in size. Probably but 
two or three of these condenser plates will be necessary if 
they are connected in multiple. For high frequency coils, 
the condenser will be somewhat larger than for general 
radio work, but the experimenter will not need to make 
more than half a dozen of the 8 x 10 plates to insure ample 
capacity. 



CHAPTER VIII. 
KICKING COIL APPARATUS. 

The possibilities of the ''kicking coil" type of high fre-" 
quency apparatus have long been recognized by manufac- 
turers of electro-therapeutic outfits but, doubtless owing 
to the scarcity of published data on the subject, this simple 
and inexpensive generator of high frequency currents has 
not seemed to come in for its due share of popularity 
among amateur constructors. 

The kicking coil is an oddity to the uninitiated elec-a 
trical worker; it is merely a winding of comparatively! 
coarse copper wire upon a core composed of a bundle of 
soft iron wires. In this simple coil, which is totally devoidl 
of a secondary, is set up a current of sufficiently high po-" 
tential to charge a condenser ; this high potential is induced 
at every break of the circuit which permits current to flow 
through the coil. 

Fig. 35 represents a circuit of this nature. The kicking 
coil K is connected at one end of its winding with one side 
of the supply circuit. The other end of the winding goes 
to the vibrating armature of an interrupter. From the sta-l 
tionary contact of the interrupter we trace this circuit ofl 
the primary of a Tesla or Oudin coil and thence back tol 
the source of supply. A condenser is connected across 
the break and the primary of the oscillation transformer. 

As the current flowing through the coil is interrupted, 
a high potential surge is set up. This current enters the 
condenser which discharges its load through the inductance 

86 



KICKING COIL APPARATUS 



87 



and across the interrupter contacts as soon as the latter 
(lose up sufficiently for the charge to leap this small air 
gap. 

By making suitable adjustments of condenser and the 
ratio between the turns in primary and secondary of the 
oscillation transformer, a high frequency current of prac- 
tically any desired frequency and voltage may be obtained, 
» within the limits of the outfit's capacity. 
The greatest merit of this apparatus is its ability to 
operate on either alternating or direct current circuits with 
merely a slight change in the number of turns in the wind- 



K 



I^ 




Pig.l 
Cirotiit for 0*C* 




Close Bwitch 
for A.C. 




Pig. 2 

drcvElt for A.C. or IV.O, 



Figs. 35 and 36. — Wiring diagrams for the kicking coil apparatus 



ing. While it is an undisputed fact that the "kicker" can- 
not compare with a transformer outfit on alternating cur- 
rent circuits, still it serves admirably in cases where direct 
current only is available. 

The ideal outfit is, of course, one that will operate with 
workable satisfaction on both direct and alternating cur- 
rent circuits ; the latter to comprise various frequencies 
found in common use. The design ofifered herewith incor- 
porates all of these desirable characteristics through the 
introduction of a variable condenser and an extra kicking 
coil. The latter is short circuited when the outfit is used 



88 



HIGH FREQUENCY APPARATUS 



on alternating current circuits. Fig. 36 gives a diagram 
of the connections. 

This outfit is capable of doing efifective X-Ray and 
general electro-therapeutic work within the inevitable 
limits of the portable outfit. The spark produced is of 
good quality and in length it reaches fully 7 inches. If the 
oscillation transformer were to be made larger in diameter, 




Side Elevation. 



End Elevation. 



Fig. 37. — Details of the vibrating interrupter 

the spark length could be materially increased without any 
alteration in the exciting apparatus. 

For the lecturer or the experimenter the outfit is an 
exceptional one. It is light in weight, inexpensive and 
simple to build, and, as we have already noted, it is uni- 
versal as regards current supply. 

The Interrupter. — This is the one weak point in the 



n 



KICKING COIL APPARATUS 



apparatus. While large and elaborate rotary contact break- 
ers are more reliable in operation, they introduce too much 
weight and cost in an outfit of this nature. The next best 
is probably a simple vibrating interrupter with massive 
contacts similar to that shown in Fig. 37. 
M The posts for the interrupter should be of generous 
proportions as the drawing indicates. The stock is of ^ 
in. square or hexagonal brass rod. The latter is preferable 
if the worker is possessed of a lathe as it may be conven- 
iently gripped in the universal chuck for cutting, facing off 
and drilling. 




















/e 






u 


/ \ 

;' O :■ 




Find with 1000 tuma 
of No. 22 enameled wire 

72 tuma per layer 
14 layers deep 


Sn»ll choke coil 
L 3- 1 




L/'. 


r 








;& 


£ 




"f 





Fig. 3S. — Small choke coil in detail 

The spring should be of phosphor 1)ronze ; the thick- 
ness is preferably in the proximity of 1/32 in. At one end 
of the spring is screwed the armature of soft iron or cold 
rolled steel rod. This is simply formed by cutting off a 
Y% in. piece of ^ in. rod. A hole tapped into the armature 
takes the short length of 8/32 threaded rod that serves to 
hold the silver contact and armature to the spring. 

The contact is cut from a length of -f^ in. pure silver 
rod. The little cylinder is to be drilled and tapped to a 
depth of Yz in. to take the 8/32 rod. 

The stationary contact is so designed that the tension 



90 



HIGH FREQUENCY APPARATUS 



of one contact against the other, may be regulated to a 
nicety. This is effected through the medium of a fine 
thread on the adjusting screw which is of y^ in. diamete/ 
brass rod. The silver contact cylinder is driven into a hole 
drilled in the end of the adjusting screw. The reverse end 
of this screw is tipped with a fibre knob of good size. 

The Choke Coils. — The smaller of these coils, Fig. 38, 
serves as a magnetic device to actuate the interrupter. It 
consists of a core of soft iron wires formed into a bundle 
^ in. in diameter and 4 in. long, covered with several layers 
of empire cloth; over this is a winding of 1,000 turns of 
No. 22 D.S.C. or enameled wire wound 72 turns per layer 



m 
^ 



Wind with 1176 turns of Ko.SO enaaeled or 
D.C.C. wound two in parallel. 

84 double turns per layer 
14 layers deep 



^i^ 



L8a*ge choke coil 



■^i-J 



Fig. 39. — Large choke coil in detail 

and 14 layers deep. A turn of empire cloth is interspersed 
between each two layers of wire. 

The core is supported between heads of fibre that fit 
closely over the bundle of iron wires. A good construction 
is to form a spool of fibre tubing with square fibre heads, 
forcing the core wires into the tube after the winding is 
completed. As the drawing shows, the layers of wire dc 
not come quite out to the end of the layer of insulating 
cloth ; this affords ample protection to the end turns which 
are subjected to maximum potentials. 



I 



KICKING COiL APPARATUS 91 



The larger of the coils is shown in detail in Fig. 39. 
The core is 6}i in. long and ]4> in. in diameter. The wind- 
ing is of No. 20 D.C.C. wire wound two in parallel. Each 
layer comprises 84 double turns and there are 14 layers in 
all. The same rules as to insulation apply as in the case 
of the small coil. 

The Condenser^ — This is of the glass plate variety in 
the present design. If the builder cares to invest in mica 
plates of the same size, he will effect a material saving in 
space and weight. 

The glass to be used is of the variety known as ''lan- 
tern slide cover glass.'' As the name implies, the glass is 
used to cover the photographic positive in a lantern slide. 
The cover glasses are thin and perfectly free from bubbles 
and the usual defects. They may be purchased from al- 
most any photographic dealer and the standard size is 3 x4 
inches. 

For the condenser at its maximum capacity, 200 plates 
of glass will be required. While this large capacity is not 
always in use, still it is essential for certain classes of work 
and it should therefore be provided. 

The conductor for the condenser is heavy tin foil. 
This comes in sheets 6^ x Syi in. and 27 sheets weigh a 
pound. For our condenser 200 pieces are to be cut 
2}i x4^ in., and for this operation a photo trimmer is well 
adapted ; lacking this, the foil may be placed on a large 
sheet of glass and cut with a sharp knife. 

The condenser is to be assembled into 20 units of ten 
plates each. This makes for convenience of adjustment. 
Each little unit will have a capacity of approximately .005 
mfd. and the entire condenser therefore reaches .1 mfd. 

When the assembly is started the builder should pro- 
vide himself with a small gas or spirit lamp, a lump of 



HIGH FREQUENCY APPARATUS 



\\X \\ 3-.v^^ 



^fV 



^^ 



♦i- 






f^ ^%\\^ Xyv^ 



~\ 



lTo.2 Sheet 
of tinfoil 




Tinfoil sheet 



Glass plate 



imit of 10 plates 
assembled ready 
for T>lnding 




20 complete iinlts in case 



Fig. 40. — Details of the condenser 

beeswax, and a tuft of cotton wrapped in a piece of sofi 
cloth. These accessories on a work table, with the clea; 
glasses and sheets of tin foil, will enable the worker to 
proceed. 



i 






KICKING COIL APPARATUS 93 

With reference to Fig. 40, the first plate of each unit 
is to have its foil sheet projecting to the left. This leaves 
a margin of }i in. on three sides. This first sheet of foil 
is to be secured to the plate in the following manner: 

Slightly warm the glass over the flame and immediately 
touch with the beeswax; spread the latter is a very thin 
layer with a tuft of cotton. Place the foil sheet in position 
and rub into perfect contact, using the dauber, and working 
outward with a circular motion. 

When this first sheet has been secured to the glass, the 
latter may be placed on the table with the foil underneath 
and projecting to the left. A touch of the wax to the 
upper side of the plate and the second foil sheet may be 
laid on; this is to project to the right with a margin of }i 
in. on top, bottom, and left side. Next comes a piece of 
warm glass with its drop of wax; then the third sheet of 
foil which projects to the left the same as sheet No. 1. On 
I this is the third plate of glass, fourth sheet of foil, and so 
j on until 10 sheets of foil and ten plates of glass have been 
assembled as shown in Fig. 40. 

The object of the drop of wax is merely to insure that 
the glass and foil sheets will maintain their relative posi- 
tions during assembly. The unit is now to be ''backed up" 
on either side with a piece of cardboard. The projecting 
lugs are rolled up with a piece of ys in. copper ribbon en- 
folded, and the entire unit bound firmly with linotape at 
top and bottom. This general procedure is to be followed 
with each of the 20 units which will then be ready for 
impregnation. 

In a double boiler, melt equal parts of beeswax and 
rosin ; in this compound suspend the condenser units for 
two hours. If the wax has been kept sufficiently hot the 
interstices between the glass plates will be completely filled 



94 HIGH FREQUENCY APPARATUS 

and each unit will form a homogeneous mass that is both 
electrically and mechanically sound on cooling. 

The Oscillation Transformer. — This may be either of 
the Oudin or the Tesla type. For the sake of simplicity^ 
the former is preferable. In order that the fullest benefit 
may be derived from the exciting apparatus it is essential 
that the primary and secondary of the oscillation trans- 
former be closely coupled. This is efifected by means of 
the spirally-wound or ''pancake'' type of Oudin coil. 

This coil is wound in a success of layers in flat or 
pancake form as its name implies. The wire is No. 30 
D.C.C. and the insulating material between layers of wires 
is oiled paper V/z in. wide and .003 thick. 

The post shown in Fig. 41 is of hard rubber. While 
the rod is held in tlic cliuck a J4 ii"^- hole is drilled clca 
through. The tail stock center is then brought up to bea 
in the hole to prevent chattering and the end of the post 
is finished ofif. A cut-oflf tool introduced at the correct 
position finishes the rubber rod. 

The hole at the base of the rod is to be tapped out 
i%-18. A length of 54 i^"*- brass rod is then forced in from 
the top of the post and cut oil when it has entered to with- 
in \y2 in. of the base. The top is threaded to enter a dis- 
charge ball and near the bottom a small hole is drilled 
through the hard rubber rod and into the brass to take 
an escutcheon pin which forms a means of connection. 

The rubber post is then to be screwed on to an arbor 
threaded /e-lS with a large disc of metal or wood between. 
Upon this rig, the pancake coil is to be wound. 

The. winding may be done either in the lathe or, if 
none is available, in a simple, home-made winder. The 
starting end of the wire is soldered to the head of the es- 
cutcheon pin that makes connection with the central rod. 
Taking three turns of the oiled paper over the rubber post, 



a 



KICKING COIL APPARATUS 



95 



and turning the lathe backwards or away from him, the 
worker may start the winding over the oiled paper. The 
first layer must have its turns separated ^ in. Over this 



Hole for 
eleotrad© 

terminal 



Hard rubBer 
poat 




Pill inside of 
case with wax ; 



A 



VTTTZZZZi 



Discharge ball 




V////// / ////// / //7 777??^. 



'^//^^///yy//////y^y/y>///y//^y////////////yyyz7. 



1 



Finishing end of •soondary 
and starting turn of priaary 
connect with this pottt 



But arbor 
held in 
lathe spindle 




Winding is done on bard rubber post 
Layer of wire 1* wide 



Connect first tiam with >rasB rod ruraiine. 
through post of hard rubber 



Fig. 41. — Details of the oscillation transformer 

layer of wire are placed three more layers of paper: then 
another of wire with turns spaced ]/% in. This is repeated 
until 50 layers are in place, the turns being gradually 



i 



96 HIGH FREQUENCY APPARATUS 

placed closer together until, with the 50th layer, they are 
separated only 1/32 in. 

From this point on and until the 150th layer, whic 
completes the coil, has been wound, the turns may b 
spaced about 32 to the inch. The layers should be but on^ 
inch in width in order that a margin of ^ in. may be lef 
on either edge. The final layer of wire is to be covered 
with 10 layers of oiled paper, the end of the winding being 
brought out ready for connection with the primary. 

The primary consists of 10 turns of copper ribbon, 1 in 
wide, wound spirally around the secondary pancake. Be- 
tween the turns of the primary is a strip of corrugated 
board such as is used for packing purposes. The finishing 
end of the secondary is soldered to the starting end of the 
primary and at this point a length of flexible lamp cord 
connects to the junction of the two. The ten primary 
turns are then wound and a tap of lamp cord taken from 
the upper edge of each of the turns from the third to the 
tenth inclusive. This provides a means of varying the pri- 
mary mductance while tuning the apparatus. The final 
primary turn is held mechanically by means of a wrapping 
of several layers of oiled paper ; the latter may be shel- 
lacked in place. 

Removing the coil from the lathe, we now have the 
complete winding ready for impregnation with the com- 
pound already suggested for the condenser. The entire 
coil is to be immersed in the molten wax for several hours 
and, before its removal, the heat should be withdrawn in 
order that the mass may partially congeal. As the wax 
shrinks on cooling, it is essential that the substance be 
permitted to contract within the coil. 

While the winding is being treated, the worker may 
build the box that is to contain the oscillation transformer. 



KICKING COIL APPARATUS 



97 



The case may be square and deep enough to permit of an 
inch of wax above and below the coil. It is obvious that 
the box must be wax-tight for the molten compound is to 
be poured into this container. 

Assembly. — For experimental purposes, the component 
parts of the apparatus may well be mounted upon a com- 
mon base board. For portable purposes such as upon the 
lecture platform or with the physician, a cabinet totally 



© 



1 I I I I I I I I i 1 1 I > I I I I I I 



i 



® 



1^^ o 

, ® 




r® 



® 



W 



u M fei y feky y 




Condeneer 

Large coil 

Shunting switch; 

Eaall coll 

Ground tersilnal' 

Interrupter 

Ualn swltcl: 

Oecillatloa 
transfomer 

Variable oocpo 
nection to 
primary 



Fig. 42. — Suggestion for assembly of apparatus upon a common base board 

enclosing the outfit will be found more satisfactory. The 
method of mounting is optional with the individual and, 
for the sake of simplicity, the apparatus is shown ready 
for use on a base board in the appended drawing. 

The connections will be clearly understood on refer- 
ence to the diagram in Fig. 36. For direct current work, 
the large kicking coil is left in the circuit, while for use on 
alternating currents, it is short circuited with the single- 



98 HIGH FREQUENCY APPARATUS 

pole, single-throw switch shown in the illustration. The 
letters "A.C' and ''D.C/' should be plainly stamped be- 
neath the respective clips of the switch as indicated in the 
diagram to prevent possible confusion. 

The capacity of the condenser is varied as may b 
found necessary by means of the copper strips which ar 
forced into the clips projecting from the condenser case. 

In operating the apparatus, the adjusting knob of the 
interrupter should be in the ''open'' position. Turn the 
current on and screw the contact in gradually. As soon as 
contact is made, the interrupter will begin to vibrate and 
a sputtering spark will form at the break of contact. The 
operation should start with about half of the condenser 
capacity thrown in and with half of the turns of the Oudin 
coil primary in use. Perhaps a spark will be in evidence 
at the ball terminal of the oscillation transformer if the 
ground terminal is brought up to within a couple of inches 
of the ball. If not, try an adjustment of the capacity in 
the condenser or a variation of the primary turns. This 
will show some improvement and the operator may then 
screw in the vibrator contact a bit further ; a considerable 
increase in length and thickness of spark will result. A 
further adjustment of capacity or inductance and a tenta- 
tive tightening of the contact will tune the apparatus per 
fectly until the maximum results are obtained. 

Electro-therapeutic Work. — The outfit described is ad 
mirably adapted for light X-Ray and vacuum tube work. 
If a D'Arsonval current is desired for auto-condensation, 
the builder is strongly advised to make a second oscillation 
transformer in which the primary has five turns and the 
secondary ten turns of copper ribbon. This coil may be 
simply constructed by winding up 15 turns of ^ in. copper 
ribbon in a flat spiral with a strip of the corrugated paper 
between to insulate one turn from the other. The kicking 



J 



KICKING COIL APPARATUS 



99 



coil current is sent through the inside turns, say up to 
four or five, and the D'Arsonval current for the couch is 
taken from the remaining turns. The diagram, Fig. 43, 




tj86 fi79 inelds tunift 
Qfl priaary 



Ufl© re=ftining t6n turni 
&8 secondary 



Coil for D'Arsonval currents 
Is conposed of a spiral winding 
of copper ribbon in IS turns 



Fig. 43. — Coil for the production of D'Arsonval currents 

makes this perfectly clear. The coil may be sealed up in a 
flat wooden case with taps brought from the respective 
turns of copper ribbon to binding posts on the outside of 
the case. 



CHAPTER IX. 
ONE-HALF KILOWATT TRANSFORMER OUTFIT 



1 



If the experimenter is the fortunate possessor of a sup- 
ply of alternating current from electric lighting mains, he 
may well devote his energies to the construction and use of 
transformer apparatus rather than bother with either the 
induction coil or kicking coil outfits previously described. 
The transformer is easily and cheaply made, and, in results,! 
it is, beyond any doubt, superior to any other device for the' 
charging of condensers. 

The Core. — The transformer core is composed of thin 
sheets of silicon steel which is prepared expressly for trans- 
former cores. The core is built up to form a hollow rec- 
tangle as shown in Fig. 44 which gives the overall dimen- 
sions. The first step is to procure the silicon steel cut to 
size; this procedure is recommended rather than attempt- 
ing to cut the large sheets in the home workshop. Unless 
a gate-shear is available the job is a slow and very unprofit- 
able one as the pieces will not lie flat if cut with an or- 
dinary pair of tinner's shears. The core irons may be pur- 
chased cut to size at a reasonable price. 

The core irons are procured in two sizes. Fig. 45, for 
the ends or legs of the core and for the sides or yokes. Of 
each size, 230 pieces will be required. The windings are 
placed on the shorter legs of the core, i. e., the legs made 
up of the 2x4^ in. pieces. These pieces are to be built 
up in two piles, the pieces being placed with ends over- 
lapping alternately first to the right and then to the left for 

100 



ONE-HALF KILOWATT TRANSFFORMER OUTFIT 101 



a distance of 2 in. as shown in Fig. 45. AYhen each bundle 
has been built up to a thickness of 2 in., friction tape 
should be wrapped around the center or winding space to 







^ 








^ 










^ 


<^ J\^^ 








^" 








' 


y:^ 






— V— 


1 0" 

— 1 ^1 


^ 





Fig. 44. — Core of transformer with dimensions 

compress the sheets into a compact bundle. If the sheets 
are clamped in a vise and the tape wrapped around the pro- 
jecting end, the core may be tightly bound as the bundle 
is released an inch at a time. 

After the two bundles have been formed, they may be 
joined by interleaving the 2x7^ in. pieces to form a yoke 
betw^een the short legs. The fourth side of the hollow rect- 
angle is not to be built up until after the windings have 
been placed in position. 




Core /ron6 

250 PC^ , 2"x4f 
250 PCS. 2"^7f 



3u/7cf (/jo 2 of f/7ese 



Fig. 45. — Short leg of core upon which winding is placed 

Primary Winding. — Fig. 46 gives the data for the pri- 
mary winding to use for any of the commercial frequencies. 



102 



HIGH FREQUENCY APPARATUS 



The core is so generously proportioned and the quality of 
iron specified so good that the only change necessary for 
use on various frequencies is in the number of turns of 
wire. 

The primary is wound upon the form illustrated in 
Fig. 48. If the builder has a lathe, the form may well be 
mounted upon an arbor or even upon the faceplate. The 
No. 14 D.C.C. wire is wound upon a base of several layers 
of oiled paper 2j4 in. wide. In preparing the form for the 




D/am.af 60^ 



PrJmory cfafo 
For //o /o/fj 



/4 D,C.C 



J 



1^ 



462 turns 

60 '^ 
257 furns ^/4 D.C.C. 



^ 



/2S fL/r/?6 



_L 



/4 D.C.C 



for 220 yo/fs use fi/v/ce as manj^ of /jdcc 



Fig. 46. — Data for primary winding 

winding, a layer of cord is first wound over the wooden 
drum, and the base of oiled paper placed over this layer of 
cord. The object of the cord is, of course, to permit the 
winding to be removed by pulling out the cord. 

Between each layer of wire and its neighbor, four turns 
of the oiled paper should be taken. This will make the 
winding, firm and smooth and it serves further to aid in* 
the insulation. The winding, when completed, is given a* 
liberal coating of armalac. The starting and finishing ends 



ONE-HALF KILOWATT TRANSFFORMER OUTFIT 



103 



of the winding are soldered to lengths of incandescent lamp 
cord which are subsequently joined to the primary bindin;:^ 
posts. 

Secondary Winding. — The secondary data is given in 
Fig. 47. This winding is of enameled wire and the method 
of procedure is identical with that of the primary. The 
same form is used and the winding started upon a heavy 
layer of micanite sheeting cut 2^ in. wide. In all, this 



7/7/6 (//o/v. for 

60'-O/7/j/ 




6eco/?^on/ c/afo 
For sooo yo/f6 

52000 tarnsS ^54 e a 



60^ 

/64S0 ri/rns *32 e/7. 



/25- 



0^ 



6240 tC/r/?6 32 6/0 



Fig. 47. — Data for secondary winding 

insulation should be about ^^ in. thick. The top turn of 
micanite is covered with several layers of oiled paper, after 
which the winding may start. 

Before starting the paper turns over the micanite, the 
builder places a strip of thin copper ribbon across the mi- 
canite. Over this the paper is wound. The starting end 
of the fine wire is to be soldered to the tip of the copper 
ribbon and as the layer of wire is wound, the ribbon is se- 
curely held. The layers of wire in the secondary are to be 



104 



HIGH FREQUENCY APPAR.\TUS 



2 in. wide to leave a margin of ^ in. on either side of the 
wire. Two turns of oiled paper are taken over each layer 
of wire before the next layer is wound. The finishing 
layer of wire is terminated m a second copper ribbon which 
forms the secondary lead for connection to the high tension 
terminals. Over the final layer of wire, several layers of 
oiled paper are wound to form a mechanical protection for 
the delicate wire. The edges of the coil are well soaked 
with armalac and the secondary is then ready to mount, 
after the compound has dried. 

, ,• Wind bofh Primary 

— ^ [ and Secondary 



i 





- Fasten fo Work Bench 



Fig. 48. — Winding machine for both primary and secondary 

Assembling and Mounting, — In Fig. 49 the complete 
transformer is shown with primary and secondary in place 
and the remaining core irons in position to complete the 
magnetic circuit. The space between the winding and the 
the core is to be partially filled with wooden plugs, care- 
fully whittled to fit the space without forcing. 

Fig. 50 suggests the mounting for the complete trans- 
former. The case may be of mahogany, oak or whitewood. 
It is built to fit the transformer and as the windings forj 
different frequencies change the diameter of both primary 



I 



n 



ONE-HALF KILOWATT TRANSFFORMER OUTFIT 105 



and secondary, and consequently the length of the complete 
transformer, the dimensions are not given in the drawing. 
The core is gripped between lengths of wood and the latter 
pieces are secured by means of screws passing through the 
walls of the case. 



SIDE IB0N5 FITTED IN ONE BY ONE. 




SECONDARY 





\ 
PEIMACY 



PU.fikN 





ELEVATION 



Fig. 49. — The transformer assemhled 

I The primary and secondary leads are brought to suit- 

able terminals in the case and the job is finished. For 
I safety to the transformer secondary, a permanent gap 
j should be affixed to the secondary terminals as shown in 



106 



HIGH FREQUENCY APPARATUS 



Fig. 50. This gap is to be not more than ^ in. in length. 
Oudin and Tesla Coils. — Fig. 51 suggests the design 
for a very practical form of Tesla coil that is easily and 
cheaply built. Fig. 52 gives the data for an Oudin coil, 
the construction of which is very similar to that of the 




Fig. 50. — Transformer in its case 



Tesla. The description herewith will accordingly be de- 
voted to a discussion of the latter type only. 

With reference to Fig. 51, the base, 1, is of suitable dry 
wood as is also the upright support, 2. The dimensions 



ONE-HALF KILOWATT TRANSFFORMER OUTFIT 107 




Fig. 51. — Oscillation transformer composed of two Oudin resonators placed tase 

to base 



108 



HIGH FREQUENCY APPARATUS 




Oucf/'n co/I dofo. 

Pn'mory : s turns edgem'se 
wound copper s/r/jo /of/, d. 

Secondare/- eoo turns 28 d.cc. on 
cardboard cyt/nder e'^/s" 



Fig. 52. — Data for Oudin resonator 



ONE-HALF KILOWATT TRAXSFFORMER OUTFIT 109 



mnd details of these parts are given in Fig. 53. The up- 
right is secured to the base by means of stout brass screws 
passing up through the base. 

Upon the upright piece, 2, is mounted, on either side, 
the primary coil of the oscillation transformer. The com- 
plete coil is really two Oudin resonators placed base to 
base with primaries and secondaries in series. The details 
of the primaries are given in Fig. 11 and the reader will 
note that the primary conductor is of edgewise wound cop- 
per strip, held in suitable supports of fibre. These sup- 
ports are detailed in Fig. 54 at 3. 




Fig. 53. — Woodwork for oscillation transformer 

The secondary coils are of 400 turns each, of No. 30 
D.C.C. copper magnet wire, wound in a single layer upon 
a cardboard cylinder 6 in. in diameter and 8 in. long. In 
either end of each cylinder, a wooden head is affixed. The 
details of the cylinders and heads are given in Fig. 55. 
After winding the cylinders, the layer of wire should be 
given five coats of shellac, each coat being dried out thor- 
oughly before the next is applied. 

The secondary discharge rods are show^n in detail in 
Fig. 54, together with the clips which hold the ball on the 
rod. The two primary coils are connected together as 



110 



HIGH FREQUENCY APPARATUS 



shown with the neutral point attached to a ground connec- 
tion. The secondary windings are likewise connected to- 
gether and their neutral point grounded at the same place. 
Condenser and Spark Gap. — The condenser, Fig. 56, is 





P05T-FlbiaE-6CEQ 



A TUENS 



^TUCNS 



PI2IMAI2.Y - 1 I5E.Q. 




Ball CUP- 2.Q.E.Q.. 



"a- 



-^'i^ 



DISCHACGL COD- a REQ^ 



Fig. 54. — Details of primary, primary support, ball clip, and discharge rod 

composed of three units of .01 mfd. each connected in mul- 
tiple. Each unit is formed by coating both sides of 8 x 10 
photographic negative glasses with 6x8 in. sheets of tin- 
foil, and assembling ten of these plates into a bundle a 
shown in the illustration. 



Lugs are brought out alter 






I 



ONE-HALF KILOWATT TRAXSFFORMER OUTFIT 111 



nately first to right and then to left in the usual manner 
and these lugs soldered to a common connector on either 
side of the unit. 

The spark gap, Fig. 57, is simple in construction. This 
design is quite satisfactory, however, for experimental work 
'on small-powered outfits. The electrodes are of battery 
zinc, }i in. diameter. A single zinc cut in two will answer 
well. The electrodes are held in supports of brass rod, 
suitably drilled and help upright upon a base that should 
preferably be of marble. If marble is not available, hard 



^4" To fit inside ofcy/inc/er 



K 



vo 



® 




sSeconcfory cyifncfer^ z re(^'d 



Fig. 55. — Details of secondary cylinders 

i wood will answer. Slate should not be used as the minute 
j metallic veins found in some varieties render the substance 
i unsuitable for this purpose. 

Connecting and Using. — Fig. 58 shows how to connect 
the apparatus. The spark gap is placed across the sec- 
ondary terminals of the transformer. The condenser is 
inserted in one lead from the gap to the primary of the 
Oudin or Tesla, while the other connection from the pri- 
mary goes back to the gap. 

When the current is applied, the ball of the Oudin or 



112 



HIGH FREQUENCY APPARATUS 



the discharger of the Tesla should give out a large brush 
discharge of purplish fire. If the first trial does not result 
in this, try a variation of the primary turns of the oscilla- 
tion transformer. This, together w^ith a variation of the 
spark gap, will serve ultimately to bring the apparatus to 
the point of resonance. The Tesla coil will give a full 16 
in. spark with the }^ k.w. transformer described in the early 
part of this chapter. 

The spark from the oscillation transformer is perfectly 
harmless if taken through a metal rod grasped firmly in the 
hand. No sensation of shock whatever will be experienced. 




Fig. 56. — Data for the condenser 

If the discharge touches the bare skin, the current will 
leave a blister if applied for any length of time in one spot. 
Aside from this unpleasantness, no direful results may be 
expected. 

Whenever the apparatus is operated, the ground con 
nection shown in Fig. 58 should be religiously made. Thij 
connection will protect the windings of the low frequencj 
transformer and also the line wires and meter in the house 



ONE-HALF KILOWATT TRAXSFFORMER OUTFIT 113 



l-'or further protection from "kick back'' on the line, place 
two small telephone condensers in series across the line 





o 


^BATTEEY ZINC 
/ 


w 





pi 
'^^:^ ft 


1 1 


o 




t-- 



7'- 



Fig. 57. — Simple zinc spark gap 

wires where they connect to the transformer and ground 
the neutral point. 









II 


? 


< 
< 

— 






?^ 


— 


3» ( 




* 

T 


II 


Li 










n 








C T- 1 










- 1 



Fig. 58. — Diagram of connections 



CHAPTER X. 
QUENCHED GAP APPARATUS. 

Comparatively few experimenters with high frequency 
current phenomena and apparatus within the acquaintance 
of the author have used the quenched gap in their experi- 
mental work. Possibly this is due to the scarcity of data 
on the construction of gaps adapted to the purpose; possi- 
bly to the lack of practical knowledge on the part of the 
workers. High frequency apparatus is so easy to build, 
and with a given expenditure of time and labor the results 
are so great with even mediocre equipment that the casual 
experimenter is likely to devote his hours to making the 
sparks fly rather than to devise ways and means for in- 
creasing the efficiency of this apparatus with a correspond- 
ing increase in the quality of the results obtained. 

The Quenched Gap. — The quenched gap to be de- 
scribed combines a number of very desirable features from 
the amateur mechanic's standpoint. It is admitted that 
there are certain inherent defects in the design, but these^ 
have to be tolerated in order that the gap may come withi 
the limits of the amateur's shop equipment, which i 
usually confined to a small bench lathe and a few other 
tools. One improvement that might be made in the gap is 
to be noted in connection with the means for adjusting the 
distance between the electrodes. If the upper electrode 2 
were cast in one piece integral with the hub or spindle 3 the 
gap might be varied in length by threading the spindle 
through the top frame plate 5. This construction presents 

114 



I 



QUENCI^ED GAP APPARATUS 115 

some very fine machine work, and a screw-cutting lathe is 
positively essential. Assuming that the latter tool is not 
to be found in the average amateur shop, the design has 
been modified so that the threading may all be done with 
taps and dies, and the only lathe work required is the 
facing-ofif and drilling operations that may be done in a 
small bench lathe with a slide rest. 

The effects produced with the high-frequency coil in 
connection with a quenched gap are truly remarkable. In- 
stead of the thin, wiry spark ordinarily seen, the discharge 
takes the form of a flame as thick as a man's wrist when 
conditions are right. At times the actual length of the dis- 
charge' is reduced, but with everything in resonance an 
increase both of thickness and length will be noted. 

With reference to Fig. 59, which is a sectional view of 
the complete gap, the reader will note the instrument is 
comprised of two cast copper electrodes, 1 and 2, which 
are held rigidly, with their faces only slightly separated. 
The lower electrode is permanently secured to the lower 
iron casting of the frame 6, while the upper electrode is ar- 
ranged to be raised or lowered by turning the insulated 
knob 14, which is fastened to a brass bushing 13. The 
spindle 3, which carries the electrode 2, is of cold-rolled 
steel, threaded iV18 for a distance of I-^q in., when it en- 
ters the electrode, then turned to J^ in. for the central 
portion and finally threaded for 1-^^- in., with the jq-IS die 
for the remaining portion. 

The electrode is held from turning by the two steel 
pins 7, which are driven into holes in the electrode and 
v/hich slide freely in holes in the frame above. Obviously, 
therefore, the movement of the upper electrode is a vertical 
one without any twist or turn. The coiled spring 8, serves 
to keep the necessary tension on the movement. 

The builder will be required to do some simple pat- 



116 HIGH FREQUENCY APPARATUS 



^ 



tern making, but this need not alarm him. It is to be de- 
plored that the average amateur has such a pronounced 
antipathy to anything in the nature of a pattern or a cast- 
ing, whereas the latter is frequently the simplest way out 
of a given difficulty. The pattern for the electrode castings 
is illustrated in Fig. 60. It is turned out of a block of 
white-wood secured to the faceplate of the lathe, care being 
taken to leave the extra stock on the edge to provide the 
necessary draft. When the pattern has been turned out it 
should be sent to the nearest foundry for a pair of copper 
castings as nearly pure as the shop can supply. 

Given the copper castings the worker grips No. 1 in 
the lathe chuck by the outer edge with the sparking face 
of the casting next to the face of the chuck. A good chip 
is taken ofif the projecting portion to remove the scale and 
the face finished with a light cut. . The centering tool is 
then brought up in the tailstock and the casting centered. 
A ^ drill is next run very carefully through the casting 
and this is followed with the j^-lS tap, which should be 
started with the tailstock center against it to insure ac- 
curacy. The hole threaded, the casting may be removed 
from the chuck and laid aside temporarily while exactly the 
same operations are done on the No. 2 casting. This latter 
must also have holes drilled to take the pins 7 after the 
casting has been removed from the lathe. So far the 
worker will have faced ofif the hubs of the castings and pro- 
vided the tapped holes for the spindles, and this in a man- 
ner that insures that the spindle will be truly at right 
angles to the plane of the hub. 

The next operation is to prepare the spindles for facing 
ofif the sparking surfaces of the castings. The spindle 3 
is first prepared. It is to be used as an arbor upon which 
both castings are faced ofif. A piece of j% in. diameter 
cold rolled steel rod is cut ofif 4 in. long and each end faced 



QUENCHED GAP APPARATUS 



117 



A 



r 





, 


\ "^ ] 






^T\ V. 


/ X 


^ m 


Ci 


T 




CD 



D 




Fig. 59. — Half-plan and cross-section of the quenched gap 



118 



HIGH FREQUENCY APPARATUS 



off and centered in the chuck, bringing its length down to 
3}i in. Holding the rod in a dog between lathe centers, 
a light cut is taken for a distance of I-^q in., bringing the 
diameter eventually down to iV in. after several cuts have 




Pattern for Nos.U2 CastingNo.l, Casting No.2j Back cjf Cast ingNo.2, Showing 

Copper Castings; Finished Siie. ' Finished Size. Concentric Rings for Radiation. 



: . I -^ UMc 



->K- 



''^■:^ 



T /J , /3"^ ^ 



l" 

■4 




N 






^ 



\ 



.TappfS" 



■ ilOlj'lli'lU'i ^ 



<---/> 



k-/"-> 



Finished 
Size 



■' .\ 



)i'T<"4 


4 ">f-.K 


Casting 


Casting 


N0.6. 


No. 5. 



<- - 7 ' 

Finished Size of Iron Casting No.5.-No.6Sim)lar; but Drilled 

Fig. 60. — Details of electrodes and frame plates 

been taken. A slight cut is taken at the end to taper the 
rod for starting a die on it and the rod is then placed in 
the chuck with the turned portion projecting. Bringing 



I 



QUENCHED GAP APPARATUS 119 



up the iVlS die with the tailstock face plate against it, the 
die may be started with accuracy and the thread taken on 
the spindle. In order to cut the thread quite up to the 
shoulder of the unturned portion of the spindle, it will be 
necessary to reverse the die taking the final cut or two with 
the die on backwards. This completes the work on the 
spindle for the present. 

Before removing the spindle from the chuck, the No. 1 
copper casting may be screwed on. The spindle is then 
removed from the chuck and replaced between centers with 
the dog as before. The surface of the copper casting may 
now be faced off with the assurance that it will be truly 
at right angles with the spindle. The edge of the casting 
may also be turned. The depression in the center of the 
casting is cut iV in. deep and 1^ in. in diameter. This 
casting finished, it may be removed from the spindle and 
the No. 2 casting put on. The facing cut is again taken, 
the depression made, and the edge turned. The entire 
spindle with the casting is now to be reversed in the lathe, 
the casting first being pinned to the spindle on which it is, 
of course, to remain. The drive this time is by means of a 
stud projecting from the faceplate and engaging a screw 
in the periphery of the casting ; the hole in which the screw 
is placed is subsequently used for the binding post, to 
which the flexible cable is attached. 

The spindle may now be turned to its finished diameter 
of J/2 in. for a space of 1^ in., and from this point to the 
end it is finished ofif to iV in. ready for threading. The lat- 
ter operation is accomplished as before by starting the die 
with the faceplate in the tailstock. 

The spindle for the lower portion of the gap casting is, 
of course, threaded -^q-IS throughout its length. This oper- 
eration is most easily done by gripping a piece of -^q in. rod 
in the chuck and threading to the required length before 



I 

f 



120 HIGH FREQUENCY APPARATUS 

cutting off. As shown in the detailed drawing, Fig. 3, 
the length of this spindle is 2-^-^ in. 

The frame plates 5 and 6 are iron castings. The pat- 
tern is a simple one that may well be cut out on a scroll 
saw, the boss for spindle and the small elevation in each 
corner being turned separately and fastened on wuth brads 
and glue. The finished size of this casting is shown in Fig. 
2. The one pattern serves for both castings, but the ma- 
chine work on each casting differs slightly from that on the 
other. As will be noted, the central hole in casting 6 is 
tapped for the iV-18 spindle, while that on casting 5 i: 
drilled and reamed to provide a good sliding fit for th 
plain portion of the spindle 3. The clearance holes for the 
pins in the upper electrode casting are also indicated i 
casting 5. A smooth file-cut on the corner bosses finishe 
the machine work on the frames after all holes have been 
drilled. 

The four corner posts are of fiber rod ^ in. in diameter 
and faced off accurately to 4% in. in length. Tapped holes 
are made in the ends for the 34"20 screws which fasten the 
structure together. 

The remaining details are obvious in construction. In 
assembling the gap, the feet and four corner posts are first 
secured to the lower frame. Then the lower electrode is 
set up tightly on its spindle in the frame. The upper 
electrode is placed on the lower and the coiled spring 
slipped over the spindle. The top frame is next slipped on, 
making sure that the pins engage the proper holes in the 
frame. The driving home of the corner screws and screw- 
ing on of the insulated adjusting knob completes the as- 
sembly, and the builder is ready to see how well he has 
done his work. The only ''snag'' is likely to be found in 
the inaccuracy of the filed bosses on the upper frame. To 
make a thoroughly good job these should have been faced 




QUENCHED GAP APPARATUS 



121 



off in a lathe at the same time as the central hole was 
drilled. To do this would require a 10-in. lathe, however, 
and in view of the admitted restrictions mentioned in the 
opening paragraphs it was thought best to omit this speci- 
fication. The facing off and drilling should by all means 
be done on the faceplate if a sufficiently large lathe is 
available. 

Quenched Gap Transformers. — The transformer for 
use with a quenched gap is essentially the same as that 




^"D^ia ( ||||||||||||||j|| -f III 

1 PEQ 



I 



Tno^-16 Ullllllllllllll^ 






© 



1 CEa 



-^£- 



@ 

- CLQ. 




® ® 






® 






STEEL -2,CEa. 



Fig. 61. — Details of the small parts 

used with the ordinary open gap. The one possible differ- 
ence worthy of mention is the secondary potential em- 
ployed. With the quenched gap, this potential may be 
considerably lower ; this change merely introduces an in- 
crease in the number of discharges per second. For certain 
classes of work, this characteristic is of material advantage, 
while for others it possesses no particular merit. 

The principal advantages to be derived from the low 
I potential secondary are as follows : The discharge from the 



122 HIGH FREQUENCY APPARATUS 

high frequency coil is thicker and hotter, although it is 
not so long; the comparatively low potential secondary 
is cheaply and easily built and insulation difficulties are les- 
sened materially ; for electro-therapeutic work, the quenched 
gap in connection with the low potential transformer gives 
a current of very high milli-amperage which is of value 
in cases where the blood pressure of the body must be re- 
duced by auto-condensation in a short time. 

The instrument to be described is of 2 k.w. capacity 
and it delivers a secondary current at a potential of 2500 
volts. The power factor is about 85 per cent, and at full 
load the primary of the transformer draws 23 amp. from 
the line on a 110- volt circuit. The winding specified is for 
60-cycle circuits but the data for other frequencies may be 
calculated as described on Page 27. As the construction of 
transformers has been covered so thoroughly in preceding 
chapters, no attempt will be made to cover the method of 
procedure. 

The core of the transformer is 3 in. square in cross- 
section and the core irons are to be provided in two sizes, 
L e., 3 by 8 in. and 3 by 12 in. Each leg of the core will re- 
quire 130 irons to build up the required three inches and 
accordingly 360 pieces of each size of iron will be required 
for the core. The core iron weighs approximately 94 lbs. 
for this transformer. This core is generously proportioned 
and the instrument may be overloaded to a considerable 
extent without ill effects as the core is not worked nearly 
to the point of saturation on a 60-cycle circuit. 

The primary winding consists of 152 turns of No. 9 
D.C.C. magnet wire wound on a round form. As the wind- 
ing space on the core is 5 in. the primary coil may be 4^ 
in. in length overall to provide the necessary ^ in. of space 
on either side for insulation. The winding may be tapped 
at the 125th, 135th and 145th turns if it is desired to have a 



i\ 



I 



QUENCHED GAP APPARATUS 123 



convenient means of over-loading the instrument. When 
the full number of turns is in use, the instrument operates 
at its rated capacity. 

The secondary winding consists of 3,454 turns of No. 
23 enameled v^ire wound in two sections. This winding is 
also done upon a round form, the air-space between wind- 
ing and core serving to keep them both cool through the 
medium of the extra radiation surface provided. Each sec- 
tion of the secondary winding may be wound upon oiled 
'paper 1^ in. wide. The winding may be carried out to 
within ys in. of either edge of the paper, which makes the 
actual width of winding 1^4 inch. The two secondary sec- 
tions are separated by a disc of fibre or, preferably, mican- 
ite sheeting, the edges of which may be bent around to lap 
over the pieces inserted between the secondary sections 
and the core. For specific instructions on the winding of a 
two-section secondary, see the transformer directions in 
later chapters. 

The magnetic leakage tongue may well consist of a 
bundle of pieces of the core iron cut 3 by 4 inch. The 
thickness of the bundle will depend upon the condenser 
capacity used with the transformer and also upon the type 
of gap employed. The correct amount can readily be de- 
termined by experiment, however, after the instrument has 
been finished and put in operation. 

Caution. — The secondary winding of this transformer 
is of low resistance and it delivers a high potential current 
that would most likely prove fatal if taken through the 
body. For this reason, more than ordinary care should be 
exercised in the handling of the instrument. If one takes 
the precaution always to make sure that the main switch 
controlling the primary current is quite open and so located 
that it cannot by any possibility fall shut while the opera- 
tor is working with the transformer, no accident can hap- 



124 HIGH FREQUENCY APPARATUS 

pen. In the experience of the author, but one serious acci- 
dent has occurred in connection with this type of apparatus 
and that was caused through the playful antics of a pet do.s: 
The control switch of the outfit was temporarily mountec 
upon the floor and the canine came bouncing along jus^ 
as a connection on the rotary spark gap was being changed 
a swish of the dog's tail and the switch came down, turning 
on the low frequency, high potential current. The shock 
was sickening but fortunately the body was well insulated 
from ground as the floor happened to be dry. It is the 
totally unexpected incidents of this nature that develop into 
real accidents. The high potential current is something 
that need not be feared, but it should certainly be respected 
The Condenser. — The oscillation condenser for thi^ 
type of apparatus may well be built up into sections of .01 
mfd. each as described in former chapters. The total ca- 
pacity required will range from .04 to .08 mfd., depending 
upon the number of turns in the primary of the oscillation 
transformer and the type of quenched gap employed. A? 
the potential is low, the condenser is not subjected to the 
strains that have to be borne by the usual type. The cur- 
rent is relatively large, however, and the plates are likely tc 
heat if the operation is maintained for any great length of 
time. For all ordinary purposes of demonstration appara- 
tus, the single units connected in parallel to give the de- 
sired capacity will answer but if the coil is to be operatec 
for say half an hour steadily at a time, as is the case in 
certain branches of electro-therapeutics, the series-multiple 
connection, in which four times the number of units are 
employed, should be used. For detailed directions cover- 
ing this condenser, refer to Chapter IV which explains the 
various methods of connection. 




CHAPTER XI. 
PHYSICIANS' PORTABLE APPARATUS. 

The design of a portable high frequency outfit for the 
ise of physicians has been approached with some diffidence. 
Such an outfit imposes certain requirements in skill and 
A^orkmanship that the amateur constructor is not likely to 
Dossess. 

The portable outfit, to be of practical value, must be 
bompact, light in weight, rugged in construction, and, 
above all, reliable and very efficient in operation. This 
kicans expert workmanship in the construction of the vari- 
ous parts and no little skill and ingenuity in their assembly 
Within a case of small compa??^.. The greater difficulty will 
be in the placing of the connecting ires and cables. These 
leads must frequently be placed in locations that are seem- 
ingly inaccessible. Should a short circuit occur within the 
case while the apparatus is in operation, the results might 
be dangerous. A large measure of the success achieved by 
electro-therapists has been due to their use of apparatus 
that could be depended upon to work at the right time and 
'thereby to establish a feeling of confidence on the part of 
'the patient. 

For the reason stated above, no attempt will be made 
to describe the construction of a protable electro-thera- 
peutic outfit of the transformer type. The high tension 
transformer is difficult of construction for the amateur in 
the very small and compact design that is necessary in this 
case. The kicking coil type of outfit lends itself admirably 

125 



126 HIGH FREQUENCY APPARATUS 






to the requirements of the practitioner, however, for wort 
at the patient's bedside and such an outfit may readily be 
constructed by the amateur worker who is the fortunate 
possessor of a few tools and some ingenuity in their use. 

Portable Kicking Coil Outfit. — In Chapter VIII, a ver} 
good outfit of this type is described in detail. The specifi- 
cations call for the various parts of the outfit mounted 
tipon a common base of wood. For the purposes of the 
physician, the entire outfit may readily be assembled in 
a wooden cabinet with handle attached, or is may be built 
into a small leather suitcase. The latter method is, per- 
haps, to be preferred as the container is more durable. 

In building the outfit from the directions given in the 
chapter referred to, the worker had best employ a mica 
condenser in lieu of the glass sheets. The mica sheets 
come in a thickness of about 1/32 in. and each sheet may 
safely be split in two as the mica has a higher dielectric 
value than the glass. The cost of the mica is, of course, i 
much higher than that of the glass but only half as much 
of the mica is required. The exact number of plates re- 
quired is dependent partially upon the speed of the inter- 
rupter and the worker may well experiment as directed in 
Chapter VIII to determine exactly the right amount of 
condenser to use before he proceeds to build the box that 
is to hold the plates. 

The discharger post of the oscillation transformer may 
prove so long that the apparatus will not go into a case of 
reasonable size. If this is the case, the post may be cut ofi' 
^n inch above the box in which the coil is mounted, and 
fitted with a plug and socket connection. The arrangement 
of the parts will suggest itself to the builder and no specific 
instructions will be given owing to the fact that the size 
of the cabinet or suitcase to be used will govern the precise 
layout of the various instruments. The description of 



PHYSICIANS^ PORTABLE APPARATUS 



127 



standard apparatus which follows will serve to offer a few 
suggestions relative to suitable arrangement. 

Standard Electro-Therapeutic Apparatus. — The stan- 
dard apparatus now on the market has reached a high stage 
of development and in many cases the physician will do 
better to buy an outfit outright rather than attempt the 
construction unless he is exceptionally w^ell supplied with 
tools and facilities for good work. The portable outfits 




Fig. 62. — Portable transformer outfit designed for vacuum 

range in price from $75.00 to $185.00 and 
the latter figure are arranged to operate on 
Ing or direct current. With the larger 
portable outfits, light X-Ray work may be 
tient's home. This feature is of prime im 
X-ray diagnosis is deemed advisable and 



tube treatment work 

instruments at 
either alternat- 
types of these 
done at the pa- 
portance where 
where, at the 






128 HIGH FREQUENCY APPARATUS 

same time, there is no other reason for moving the patient 
to the hospital. 

In Fig. 62 may be seen a reproduction of a portable 
outfit that may justly lay claim to many unique features. 
This is one of the lower-priced outfits but the price cannot 
be taken as a criterion of its value. The outfit incorporates 
an exceptionally fine control device which renders it well 
adapted to the requirements of the general practitioner or 
the specialist who uses the usual high frequency modalities 
in his work. The range of the apparatus covers everything 
but the X-ray and the elimination of this feature in the 
design is largely responsible for the low price of the outfit. 

The outfit is of the transformer type and it operates 
only on alternating current circuits ; for use with direct 
current, a rotary converter is necessary. The rotary costs 
about forty dollars and its weight detracts from the porta- 
bility of the outfit. The main consideration for the pro- 
spective purchaser is, therefore, to determine whether the 
current supply in the places where the outfit is to be used, 
is alternating or direct. If the latter is found to be preva- 
lent, a modified type of portable outfit selling at the samel 
price would serve the purpose better. 

The small transformer outfit described in the preceding 
paragraph is designed for all classes of vacuum tube, fulgu- 
ration and diathermic treatments. For fulguration the out-1 
fit is ideal as the fine control enables the operator to change" 
from a comparatively cold spark such as is used to produce 
a dehydrating action, to a hot and caustic spark. The 
principal feature of the control is found in the use of an 
interchangeable pair of secondary coils on the oscillation 
transformer. In addition to this, the ''coupling" of the 
primary and the secondar}^ is variable, which introduces 
a further refinement of control. One of the secondary unitsi 
or ''inductors" as they are called by the manufacturer, is' 



PHYSICIANS' PORTABLE APPARATUS 



129 



wound with comparatively few turns of coarse wire to pro- 
duce the hot spark for fulguration, while the other coil is 
wound with a greater number of turns of finer wire to pro- 
duce the higher voltage necessary for vacuum tube work. 

For diathermy where an exceedingly heavy current is 
made to pass through a localized area of the body, the coil 
is quite unique as it is capable of delivering a current vary- 
ing between zero and 2,000 milli-amperes between the 
diathermic electrodes. 

Direct Current Outfits. — Fig. 63 illustrates a treatment 




Fig. 63. — Portable kicking coil outfit that will operate on either direct or 

alternating current 

outfit of the kicking coil type that sells for $75.00. This 

outfit weighs but thirty pounds, will operate on either 

direct or alternating current circuits, and combines all of 

j the high frequency modalities with the exception of heavy 

i auto-condensation and X-ray work. True, it will do light 

I general ' diagnostic work as the potential is sufficient to 

break down an air gap of four inches which is sufficient to 

excite the average six-inch X-ray tube of moderate vacuum. 

i The outfit described is preferable to the transfcrmer 



130 



HIGH FREQUENCY APPARATUS 



apparatus in the event that nothing but direct current is 
available in the vicinity. No rotary converter is necessary 
and if the physician chances to be in a neighboring town 
where alternating current is unexpectedly found, the appa- 
ratus is equal to the emergency. 

For dentists this outfit is exceptionally well adapted. 
It is excellent for the treatment of diseases of the oral 
cavity and in addition it will make good radiographs of the 
jaws with comparatively short exposure. 

Large Portable Outfits. — Fig. 64 illustrates an outfit of 




Fig. 64. — Powerful portable outfit comprising both kicking coil and transformer 
for use on either direct or alternating current circuits 

the highest grade which combines the features of porta- 
bility, reliability, and general utility to a degree not ap- 
proached by the smaller outfits. The price of this equip- 
ment is $185.00 when arranged for both alternating and di- 
rect current use. 

This outfit is capable of doing all manner oi general 
high frequency and X-ray work that may come within the 
requirements of treatment at the patient's bedside. The 
various modalities can be obtained from the equipment as , 



PHYSICIAXS' PORTABLE APPARATUS 131 

follows : Static spark, vacuum electrode, fulguration or con- 
vective discharge, high frequency spray or effluve, Oudin, 
Tesla and D'Arsonval currents, unipolar current, cautery 
current, ultra-violet lamp (from alternating current circuits 
only), and currents for auto-conduction and auto-condensa- 
tion, sufficient for all local treatments. In addition to this, 
the apparatus is capable of giving very good results in 
X-ray work of the lighter type such as making radiographs 
of the extremities, fluoroscopic examinations for diagnosis 
in cases of fracture, etc. 

The outfit combines both a transformer and kicking 
coil. The former is used on alternating current circuits and 
the latter on direct. The operation is controlled by means 
of a few switches and levers and simplicity is a character- 
istic of the equipment. 



CHAPTER XII. 
PHYSICIANS' OFFICE EQUIPMENT. 

The construction of a powerful and efficient high fre- 
quency and X-Ray equipment capable of meeting all the 
requirements of the general practitioner is well within the! 
reach of the average amateur builder. 

True, the apparatus w411 not be enclosed in a handsome 
cabinet and the entire outfit will probably be somewhat 
bulkier than the manufactured article. Furthermore, the 
cost of the entire apparatus will probably be nearly as great 
as that of a professional outfit purchased complete. Them 
amateur constructor's principal reason for building his own 
outfit will probably be the experience he receives and the 
intimate knowledge of the component parts that he 
acquires during the process of building. 

The design for a 1 k.w. outfit comprising all of the 
popular high frequency modalities is contemplated. Fig. 
65 suggests the assembly of the various units upon a table 
of conventional design. Of course, all of this apparatus 
might be arranged within the walls of a cabinet, but for use 
in the office where the outfit is seldom if ever to be moved, 
the cabinet has no particular advantages over the simple 
arrangement shown in the illustration. Furthermore, the 
assembly on a table results in a most imposing array of 
instruments all of which are readily accessible for adjust- 
ment or repair. 

The complete apparatus is divided into two basic 
groups, one of which is the exciting apparatus comprising 

132 



PHYSICIANS' OFFICE FQUIPMEXT 133 

transformer, spark gap and condenser, while the other 
group embraces the oscillation or high frequency trans- 
formers, of which there are three. Of the latter, No. 6, 
the first instrument on the left in Fig. 65, is a coil of the 
Oudin type capable of producing a high frequency current 
of moderate potential for vacuum tube work ; high potential 
current of very high periodicity for producing a spray or 
effiuve ; and a current of great intensity, moderate poten- 
tial and high periodicity for the removal of moles and 
warts by means of fulguration. The maximum spark 
length of this coil is about 3 in. The winding is coarse and 
the coil may therefore be used for high potential auto-con- 
densation work. The variation in frequency and potential 
is effected by means of an adjustment of the number of 
primary turns. 

The coil shown in the center of the table, Fig. 65, is 
designed for X-Ray work. This instrument is an oil-im- 
mersed oscillation transformer which may be termed a 
combination of the Oudin and Tesla types since two Oudin 
coils are placed base to base to form a Tesla coil of sound 
mechanical construction. 

The X-Ray coil produces a thick and very hot 10 in. 
discharge between the points connected with its terminals. 
With a suitable high frequency tube, radiographs may be 
made of any part of the body in a comparatively short 
space of time. 

The oscillation transformer at the right, No. 8 in Fig. 
65, is intended for general D'Arsonval treatment and its de- 
sign is such that the work may be made to cover both auto- 
condensation and diathermy. The latter is a comparatively 
new method of treatment which consists in placing a plate 
of metal on either side of the localized area to be treated 
and passing a very heavy current of from 800 to 2,000 
milli-amperes. The frequency, potential, and intensity of 



134 



HIGH FREQUENCY APPARATUS 



the current delivered by this transformer may be varied to 
an astonishing degree by placing the clips attached to the 




Fig. 65. — Large electro-therapeutic outfit mounted upon a table 



PHYSICIANS' OFFICE EQUIPMENT 135 

flexible connecting cords on different turns of the winding. 
This wide range of adjustment permits the operator to so 
attune the apparatus that the circuits through the patient's 
body and the coil may be brought very closely to resonance. 

Reference to Fig. 68 will disclose the wiring diagram 
for the complete outfit. The reader will note that the leads 
from the condenser and the spark gap are attached to two 
copper tubes placed parallel with the X-Ray transformer 
and supported in insulating pillars secured to the top of the 
table. From this, tubes heavy flexible cables complete the 
oscillation circuit through the primaries of coils 6, 7, and 8. 

The thoughtful reader will, of course, understand that 
one coil is connected in the circuit at one time ; this permits 
of a concentration of the full output of the exciting appa- 
ratus upon the particular coil in use and obviates the 
necessity of dividing the energy among the several instru- 
ments, only one of which is used at one time. Two spark 
gaps are specified in the assembly, Fig. 65. The gap *'4'' is 
of the conventional stationary variety with nickel steel or 
silver electrodes, while the gap ''3" is of the rotary type 
with zinc stationary and aluminum rotary electrodes re- 
spectively. The rotary gap is used for the X-Ray and 
D'Arsonval coils, while the stationary gap is best adapted 
for the Oudin Coil, No. 6. The current delivered by the 
latter coil must be under perfect control and in certain 
classes of vacuum tube w^ork it is necessary that a delicate 
and perfectly steady high frequency spark be employed. 
The stationary gap suggested will enable the operator to 
adjust his current with such delicacy that the spark may 
be brought from a velvety spray a quarter of an inch in 
length to a hot, 3 in., caterpillar discharge simply through 
an adjustment of the length of gap, variation of primary 
turns and changes of the current regulator on the low fre- 
quency transformer. The rotary gap is intended for long- 



136 HIGH FREQUENCY APPARATUS 

continued treatments where the apparatus is working at 
approximately full power during the entire length of time. 
While the stationary gap is in use, the disc of the rotary 
is turned so that the electrodes are opposite the open 
spaces in the periphery of the disc ; when the rotary gap is 
to be used, the adjustable electrode of the stationary gap is 
merely opened until the spark prefers to pass by means of 
the rotary. 

A useful accessory to the apparatus is shown mounted 
on top of the D'Arsonval coil, 8. This is a hot wire meter 
that will indicate accurately the amount of current passingl 
through the patient's body while the D'Arsonval treatment" 
is being given. The design for a simple hot wire meter is 
given in the next chapter for the sake of completeness, but 
in view of the fact that a standard instrument of the typel 
shown in the illustration can be purchased for $12.00, the" 
amateur builder is scarcely justified in attempting the con- 
struction. 

The low frequency transformer, 2, which converts the 
residence lighting current into a high potential one suitable 
for charging the condenser of the outfit is a standard mag- 
netic leakage instrument with a variation in the number 
of turns in the primary. The alternating current supply 
from the house mains is connected with the knife switch 
shown directly above the transformer and from the switch 
a cable leads to the low-tension terminals of the trans- 
former. The snap switch controls the rotary spark gap 
motor. 

The condenser is the glass plate type arranged in sec- 
tions or units which may be connected in multiple one 
section at a time by means of the single pole knife switches 
shown on the top of the cabinet (5 in Fig. 65). 

For the sake of clarity and simplicity, the construction 
of the various instruments that enter into the assembly of 



PHYSICIANS' OFFICE EQUIPMENT 137 

the outfit is divided into eight sections, each part bearing 
an appropriate heading. The numbers preceding each head- 
ing correspond with the numbers assigned to the various 
instruments shown in Fig. 65 which represents the ground 
covered in the first part of this chapter. 

2. The Magnetic Leakage Transformer. 

3. The Rotary Spark Gap, 

4. The Stationary Spark Gap. 

5. The Oscillation Condenser. 

6. The Vacuum Tube Treatment Transformer. 

7. The X-Ray Oscillation Transformer. 

8. The D'Arsonval Oscillation Transformer. 

Magnetic Leakage Transformer. — This transformer is 
of 1 k.w. capacity and the data is given for windings suit- 
able for use on 110 and 220 volt alternating current cir- 
cuit having periodicities of 25, 60, and 125 cycles. This 
data will be found in Fig. 2 which gives the details of the 
transformer The specific instructions for the building of 
the instrument apply only to the 60 cycle, 110 volt winding 
as that is the one most commonly used. 

The core is a hollow rectangle of laminated silicon 
steel built up by placing rectangular pieces of the steel with 
ends overlapping alternately to the right and left as shown 
in the drawing marked ''assembly.'' Two sizes of core 
pieces will be needed, namely, 2x5^ in. and 2x6^ in. 
and 340 pieces of each size will be required. The magnetic 
leakage tongue shown in the center of the core is a bundle 
of 90 pieces of silicon steel cut 3 in. x Zy^ in. The silicon 
steel for the core may be purchased cut to size and ready 
to assemble, if desired, and this course is the wiser one to 
pursue if the constructor is not possessed of a gate shear. 

The 2x5^ in. pieces of steel are to be divided into 
two equal piles and each pile assembled with the strips 



138 



HIGH FREQUENCY APPARATUS 



alternating to such an extent that the overlap is just 2 in. 
The assembled pieces may be clamped in a vise and tightly 
bound from end to end with friction tape, releasing the 
core an inch at a time as the binding proceeds. 

The winding is done directly upon the core in the case 
of both primary and secondary. The illustration suggests 
how this may be accomplished. Two blocks of wood are 
prepared with recesses to take the ends of the core strips 






-1^^-i 



TH\5 CO^E. 

Fo;^ 

CYCLES 



ASSEMBLY 
CYCLES PJilMACY SECOND AQY 



-=4 




S,S ACQ TUBNS 
KO.ia- o.c.c. 

eo SOO TUBNS 
NO.n D.CC. 



AZS 



10O TUDNS 

rvo. 11 D.CC. 



lesoOTu 

NO. 30 En 

e400 Tu 
NO. as En. 

4200 Tu 
tVO. ZQtN. 



Fig. 66. — Data for the magnetic leakage transformer 

in order that the core may be held in the lathe for winding. 
The primary winding consists of 200 turns in all of 
No. 11 D.CC. wire tapped at 110, 140, 170 and 200 turns. 
The winding is 27 turns per layer and the first layer of 
wire is wound upon two thicknesses of micanite wrapped 
over the core. A single turn of micanite is placed between 
layers of wire to insulate the winding and to keep the latter 






PHYSICIANS' OFFICE EQUIPMENT 139 

uniform. A convenient method of making the taps in the 
primary is to solder a length of copper ribbon to the proper 
turn, insulating the ribbon thoroughly with paper where 
it passes between adjacent turns. To this tap of copper 
strip, a flexible stranded cable may be soldered and carried 
to the switch on the outside of the transformer case. 
When the primary winding is finished it may be given sev- 
eral coats of armalac and permitted to dry. 

The secondary is wound in two sections upon the other 
jleg of the core. Each section has 4,200 turns of No. 28 
enameled wire which is wound in layers 1 in. wide with 
layers of oiled paper V/z in. wide, between. The precise 
manner in which this winding is done has been covered so 
thoroughly in other chapters of this book that to reiterate 
the instructions would be superfluous. 

When the windings have been completed, the core is 
assembled by fitting in the longer core pieces in the spaces 
left between the projecting ends of the cores containing 
the Vv'indings. This is rather a tedious job, but with the 
aid of a small hammer judiciously applied, the magnetic 
circuit may be completed without undue labor. The mag- 
netic leakage tongue is wedged between the yokes of the 
jCcre by means of wooden strips. The complete trans- 
former is mounted within a w^ooden case, the dimensions of 
[which have not been given. 

The Rotary Spark Gap. — This gap may be of the stock 
.variety sold by many wireless supply houses for use in 
'connection with amateur transmitting sets of from one- 
half to one k.w. capacity. The design presented in Fig. 
65, however, is simple of construction and in use it will be 
found superior to some of the manufactured articles now 
on the market. 

!/ The rotor is a disc of ^ in. aluminum, 6 in. in diame- 
jter, and having 12 semi-circular sections removed from its 



140 HIGH FREQUENCY APPARATUS 

periphery, thus leaving a series of 12 teeth, each tooth pre- 
senting a surface of >^ x ^ in. to the stationary electrode 
mounted on either side. The rotor disc is fitted to a fibre 
bushing and this bushing is mounted upon the shaft of a 
small alternating current fan motor, which should have a 
speed of approximately 1,800 r.p.m. 

The stationary electrodes are lengths of ^ in. zinc rod 
threaded and tipped with large disc of fibre to serve as 
adjusting knobs to vary the gap between the electrodes 
and the disc. 

The entire apparatus is mounted upon a substantial 
base of dry wood. 

The Stationary Spark Gap. — This gap may be a stock 
one purchased from a wireless dealer or it may be con- 
structed to order. The design given in Fig. 65 covers a 
gap of substantial proportions and one that is designed for 
continuous operation. The gap consists essentially of the 
two nickel steel or silver electrodes, mounted upon threaded 
rods, and supported by square brass pillars of suitable 
proportions. One of the threaded rods is fitted with a 
large fibre handle for purposes of adjustment. Radiators 
consisting of discs of brass separated by washers are 
mounted in back of the electrodes in order that the latter 
may be cooled. The construction is so clearly shown in 
the drawings that no further description is deemed neces- 
sary. 

The Oscillation Condenser. — The condenser comprises 
four units of .01 mfd. capacity each, so arranged that they 
may be connected in multiple one at a time by closing the 
three single pole knife switches mounted on the top of the 
cabinet. The connections are clearly shown by the dia- 
gram in Fig. 68. 

Each unit of the condenser is composed of 10 plates of 
8x10 photographic negative glass coated on both sides 



PHYSICIANS' OFFICE EQUIPMENT 141 

with 6x8 in. sheets of tin foil with lugs projecting alter- 
nately first on one side and then on the other as the units 
are assembled. The construction of this type of condenser 
is thoroughly covered in other chapters of the book. 

The Vacuum Tube Oscillation Transformer. — This os- 
cillation transformer is of the Oudin type comprising a 
secondary of 200 turns of No. 18 annunciator wire in a 
single layer wound upon a cardboard cylinder 8 in. in di- 
ameter and 13 in. long, and a primary helix of 10 turns of 
edgewise wound copper strip having an inside diameter of 
10^ in. The primary turns are supported by rectangular 
pillars of fibre or hard rubber preferably mounted upon an 
independent base in order that the complete transformer 
may be removed from the table without difficulty. 

The top turn of the secondary winding is connected 
with the brass ball surmounting the coil while the bottom 
tui-n is connected with a common ground terminal which 
is mounted upon a copper bar running the entire length of 
the table. The bottom turn of the primary helix is like- 
wise connected with this ground terminal. 

The X-Ray Oscillation Transformer. — This coil is of 
the oil-immersed type. Fig. 67 shows clearly the method 
of construction and the reader will note that the trans- 
former is a combination of the Tesla and Oudin types. 
Two secondary coils are wound upon 6x8 in. cylinders of 
cardboard and the winding is to be of No. 22 D.C.C. wire 
wound in a single layer until 200 turns are in place on each 
of the cylinders. The turns are either to be spaced in a 
lathe or else wound with a coarse thread between, for it is 
essential that they be separated fully the thickness of a 
piece of the wire in order that the very high potential be- 
tween turns may not puncture the insulation. Both sec- 
ondary coils are, of course, to be wound in the same direc- 



142 



HIGH FREQUENCY APPARATUS 



tion as one coil is to be a continuation of the other when 
they are placed end to end. 

The two secondaries are secured to the central piece 
of wood which is fastened to the cover of the case that 
contains the transformer. The outside ends of the second- 
ary winding are connected with rods leading to the dis- 
charge balls of the coil while the inside ends are, of course, 
connected together, a wire passing through the supporting 
board for this purpose. 

The primary is composed of 8 turns of edgewise wound 

Q— = — g 




Fig. (il . — Oil-immersed oscillation transformer for X-Ray work 

copper strip 7^ in. inside diameter. The helix is divided 
in the center in order that 4 turns may be placed on either 
side of the wooden piece upon which the secondary cylin- 
ders are mounted. The primary turns are mounted upon 
slotted fibre supports in the usual manner. A tap consist- 
ing of a length of heavy incandescent lamp cord is soldered 
to each of the 3 outer turns on both sides of the helix and 
brought to its proper terminal in the cover of the case. 

The containing case should be of rather heavy stock 



PHYSICIANS' OFFICE EQUIPMENT 143 

and lined Vv^ith sheet zinc with corners carefully soldered. 
The reader will note that when the cover of the case is re- 
moved the entire coil comes out with it and there is ac- 
cordingly no necessity for attempting to make any connec- 
tions underneath the oil which fills the zinc-lined case. 

When the mechanical work on the transformer is fin- 
ished, the cabinet may be filled nearly full of transformer 
oil, or if this is not available, double-boiled linseed oil may 
be employed. The oil should be made very hot before the 
transformer is lowered into it in order that the air may be 
expelled. 

The essential details of construction are clearly shown 
in the drawing, Fig. 67. Further discussion is not deemed 
necessary. 

The D'Arsonval Oscillation Transformer. — This is a 
standard ''loose coupled'' helix of the wireless type and it 
may be purchased complete for $12.00. It is simple of con- 
struction, however, and the builder, if he so desires, may 
purchase merely the edgewise wound copper strip, making 
the slotted hard rubber supporting posts and the wooden 
heads in his own work shop. The copper helix is 7^ in. 
in diameter and the strip may be purchased already wound 
at 15 cts. per turn. The primary or lower portion of the 
transformer comprises 8 turns while the secondary or upper 
portion contains 22 turns. There is no electrical connec- 
tion between the two, the closed oscillating circuit taking 
in the primary while the patient's body is connected with 
the secondary. 

Assembly. — The entire lot of apparatus is assembled as 
shown upon a substantial table fitted wtih a shelf beneath. 

Fig. 68 gives a complete wiring diagram for the entire 
group of apparatus. The connecting wires should be of 
heavy stranded cable which may conveniently be made by 
grouping four or five strands of heavy incandescent lamp 



144 



HIGH FREQUENCY APPARATUS 



cord together and binding them into a cable with tape or 
fishline, ana soldering the ends into suitable lugs. The 
variable connections to the turns of the primary coils may- 
be clips of the conventional variety. The drawing suggests 



@ 




© 



^^ 1 1 1 1*" 

I L 




Fig. 68. — Diagram of connection for the entire outfit 

a clip of suitable design. The ground connection is abso- 
lutely essential and care should be taken to see that the 
ground terminal is connected with the nearest water pipe 
whenever the apparatus is to be set in operation. 



CHAPTER XIII. 



y 

\\ A PHYSICIAN'S OFFICE EQUIPMENT MADE 
WITH STANDARD MATERIALS. 

The materials used in the outfit described in this chap- 
ter can be purchased on the open market from the various 
electrical and supply houses. In this way a very inexpen- 
sive and highly efficient outfit can be put together. 

The complete set of apparatus is shown in Fig. 69. 




Fig. 69. — Complete, homemade office outfit for physicians' use 

This may be said to represent the essentials of the equip- 
ment without the trimmings such as controlling devices, 
electrodes, treatment chair, etc. The apparatus as shown 
will produce the high frequency current required for auto- 
condensation, X-Ray or vacuum tube treatment. The con- 
j taining case or cabinet, controlling switches, etc., will 
( form the subject of the latter part of this chapter. 

145 



146 HIGH FREQUENCY APPARATUS 

From left to right in Fig. 69 we see the transformer, 
stationary spark gap, rotary spark gap, condenser, and os- 
cillation transformer. To define the terms just given we 
may say that the transformer receives the commercial al- 
ternating lighting current from the house mains at a volt- 
age of 110 or that commonly used for running motors and 
lighting lamps in the house. The transformer converts this 
low potential ^ current into one of several thousand volts 
pressure at the secondary terminals of the instrument. 
This high voltage current ''charges" the condenser which 
consists of two groups of metal plates separated by plates 
of insulating material. When the charge in the condenser 
reaches a certain critical value, the current leaps across the 
electrodes of the spark gap, thereby setting up electrical 
oscillations or a high frequency current in the circuit con- 
necting the condenser and spark gap. 

Now, the high frequency current generated in this cir- 
cuit is of comparatively low voltage, so we must utilize the 
principle of the transformer once more to ''step up" the 
voltage to that recjuired for X-Ray and treatment work. 
To do this w^e include in the oscillatory circuit a coil or 
spiral of brass or copper ribbon, having four or five com- 
plete turns, each turn separated from its neighbors by in- 
sulating material. This forms the ''primary" or low-ten- 
•sion side of an oscillation transformer. To produce a very 
high voltage, high frequency current, we have merely to 
place within this primary a cylinder or cone of cardboard 
wound with a single layer of insulated copper wire, con- 
necting the lowermost turn of the cylinder or cone winding 
with the inside turn of the primary. From this secondary 
coil we may take a current of perhaps hundreds of thou- 
sands of volts, depending upon the number of turns in its 
winding and upon the relation of its winding to the balance 
of the circuit. 



STANDARD OFFICE EQUIPMENT 



147 



The transformer and condenser are shown in Fig. 70. 
The current is applied to the primary at the left and taken 
from the secondary at the right of the transformer. Pri- 
mary and secondary are merely coils of very coarse and 
very fine copper wire, respectively, thoroughly insulated 
and mounted upon a core or hollow rectangle of silicon 
steel built up from thin sheets placed one upon the other. 





Fig. 70. — The complete transformer and condenser 

In Fig. 71 is shown the rotary spark gap and beside it 
the small stationary gap. The rotary gap is used when the 
apparatus is working at its full power for the production of 
a long and powerful spark for use with an X-Ray tube. 
The smaller gap is used for vacuum-tube treatment work 
where a small and very mild current, under perfect control, 
is used. 




Fig. 71. — The rotary and stationary spark gap 

Fig. 72 shows the oscillation transformer w^iich steps 
1 tip the high frequency current. In Fig. 73 is showai the 
'' winding machine, of wood, upon w^hich the cardboard cone 
is wound. 



148 



HIGH FREQUENCY APPARATUS 



The oscillation transformer may be purchased, but it is 
so easily constructed that the builder is advised to attempt 
it. The first requisite is the cage upon which to do the 
winding. The construction is obvious. Three discs of 




Fig. 72. — The complete oscillation transformer 

wood are cut by means of a scroll saw and mounted upon a 
length of dowel rod which is in turn carried in the simple 
wooden uprights which form the bearings. Slats of thin 
wood are then nailed to the discs to form the conical cage. 




Fig. 73. — The improvised winding machine 

In forming the paper cone, red rope insulating paper 
should be used. This paper is heavy and stiff and it has 



STANDARD OFFICE EQUIPMENT 149 

excellent insulating properties. A disc of paper of the cor- 
rect size to form the cone should first be cut. The size of 
the cone may be varied within reasonable limits in the 
event that the builder may have some substitute for the 
v^inding rig shown. However, it is well to adhere as 
closely as possible to the dimensions given here. This 
cone is 4 in, across the top, 12 in. at the base, and 15 in. 
high at the perpendicular. 

Some assistance will be required in rolling the disc of 
paper into a cone or cornucopia before slipping it upon the 
form. The final trimming may be done when the cage or 
form is inside. Glue may be used to hold the edges of 
the paper together, but we recommend the use of shellac or 
some other insulating compound as the water in the glue is 
likely to cause trouble. When the adhesive is thoroughly 
dry, the seam may be sandpapered smooth and the entire 
surface of the cone coated with shellac preparatory to 
winding. 

The winding for this size of cone is a single layer of 
No. 22 double cotton covered magnet wire. The winding 
is started at the smaller end of the cone, small brads being 
driven part way into the slats at the end of the cone to pre- 
vent the succeeding turns of w^ire from forcing the first 
ones ofif as the winding proceeds. The base of the winding 
rig should be firmly secured to the work table before start- 
ing in. 

When a single even layer has been placed, the end of 
the wire is secured by passing it through the cone and 
plugging the hole with a toothpick dipped in shellac. 
Then the entire surface of the winding is thoroughly 
coated with shellac, care being taken to see that the fluid 
soaks well into the insulation of the wire. When this coat 
is thoroughly dry, paint a second time and a third. Make 



150 



HIGH FREQUENCY APPARATUS 



sure that each coat is perfectly bone dry, however, before 
starting the next. 

When the winding is finished, attach a wooden disc to 
the top of the cone and to this a bed-post ball of brass. 
Solder the topmost end of the winding to this ball. Sol- 
der a piece of flexible lamp cord to the lower end of the 
winding and secure in place so that the fine wire will not 
unwind in use. The oscillation transformer is not com- 
plete with the exception of its primary which is so simple 
as to need very little description. 

The primary is merely four turns of brass or copper 
ribbon, of about No. 26 gauge, and one inch wide, wound 
into a spiral 15 in. inside diameter, with turns separated 




1 



Fig. 74. — The coil used for D'Arsonval and Thermo-Faradic treatments 

by a strip of corrugated paper packing. Bindings of tape 
at frequent points hold the turns together. Connection to 
the turns is made by means of brass clips formed by bend- 
ing pieces of the brass ribbon in two and soldering a piece 
of lamp cord to the top of the clip thus formed. 

The coil used for D'Arsonval and Thermo-Faradic 
treatments is shown in Fig. 74. The smaller ribbon spiral 
is in this case made to displace the conical secondary as a 
lower potential is required. In the next article, the con- 
struction of a more efficient form of D'Arsonval coil will 
be described. 



STANDARD OFFICE EQUIPMENT 151 

This completes the description of the essential parts 
(f the apparatus. 

The cost of the apparatus will depend upon the size 
of the outfit ; that is to say, upon the power of the equip- 
ment. For instance, for light tube treatment and auto-con- 
densation work in a patient's home, it would be absurd to 
])uild an outfit of the power' of that shown in our illustra- 
tions. One quarter of that powxT would be sufficient. For 
the physician's office, however, where an X-Ray picture 
may have to be made of any part of the body, the larger 
power is worth w^hile, particularly as such an outfit is not 
very expensive. 

For convenience, we have divided our estimates into 
groups oi }iy y2y and 1 kilowatt, in size. The oscillation 
transformer may remain the same for all and as its cost is 
represented chiefly by the builder's time, this item is not 
listed. Neither is the cabinet to be described. We have 
listed only the items it will be necessary for the builder to 
purchase outright before starting construction : 
One-quarter Kilow^att : 

Transformer, magnetic leakage type S 20.00 

Rotary gap 1 7.50 

Condenser, six sections at $3.00 each. 18.00 

Stationary gap 3.00 

Safety condenser 4.50 

S 63.00 
One-half Kilowatt : 

Transformer, magnetic leakage type S 30.00 

Rotary gap 1 7.50 

Condenser, five sections at $4.00 20.00 

Stationary gap and safety condenser 7.50 

$ 63.00 



152 HIGH FREQUENCY APPARATUS JH 

One Kilowatt: 1 

Transformer $ 60.00 

Rotary gap 17.50 

Condenser 30.00 

Stationary gap and safety condenser 7.50 



$115.00 
In these estimates, the transformer is quoted in the un- 
mounted condition. There is no need for paying several 
dollars for a mahogany cabinet that cannot be used in the 




x^- ; Use^''Shck,lfno 
"" J other Size is 
V: ^p^cified. 



-<----t------f--^ --• J^-"- -1— v.;rH'-i 




A ^ ,, B C D . 

, Piec es marked ''R"Se cf/ons belowServefo Clamp Apparahis in Place,'nofindicafed above. 

"^'^^^ss:^ ^^^-.v^i^'.-.-zj Erpv.-vvVN-.yj ^^:::i2:i^s3 




B-B 



C-C^ 



D-D 



Fig. 75. — Complete details of the cabinet for the outfit 

outfit. The condensers are made in two sizes, namely, 
.0017 mfd. and .002 mfd. The latter are larger and 
stronger and are therefore used in the large outfits. The ■ 
rotary gap is the same for all outfits as are also the station- f 
ary gap and protective condenser. The latter is necessary 
to protect the house wiring from danger. 



STANDARD OFFICE EQUIPMENT 



153 



The details of the cabinet are given in Fig. 75. The 
box may be constructed of mahogany, oak or white wood 
stained and finished to suit the taste of the builder or to 
harmonize with the furniture in the office. All of the nec- 
essary details of the cabinet are given in the drawing and 
it is believed that further description w^U be unnecessary. 

Fig, 76 shows the cabinet with cover shut down and 
the following instruments mounted upon it : operating key, 
impedance and primary regulators, rotary gap, switch and 




Fig. 76. — The cabinet closed 

controlling rheostat, single pole, single throw knife switch, 
stationary gap, and inductance coil. 

Referring to Fig. 77, we have an enlarged view of the 
left-hand end of the cabinet with impedance coil removed 
to show method of mounting. This coil consists of a core 
of iron wire made up into a bundle 2 in. in diameter and 
7^2 in. long. On this core is placed a single winding con- 
sisting of 700 tvirns of No. 14 D.C.C. wire disposed in even 
layers and with eight taps taken out of the winding at the 
last eight layers. These taps, together with the starting 
and finishing ends of he coil make ten leads in all to be 



154 



HIGH FREQUENCY APPARATUS 



connected with the contacts of the impedance switch on the 
cover of the cabinet. The object of this impedance is to 
reduce the amount of current flowing through the primary 
of the transformer, when operation at full power is not de- 
sired. The impedance, furthermore, makes it possible to 
produce some very curious and valuable phenomena in 
connection with the high frequency discharge. 

The protective device, consists of two standard con- 
densers of the telephone type, having 2 mfd. capacity each. 




Fig. 77. Method of mounting impedance coil 

connected in series, with the outside leads placed across the 
primary supply wires and the neutral point grounded. 
This protective device can be purchased in the open mar- 
ket about as cheaply as it can be constructed by the ama- 
teur. Its use is absolutely essential to the safety of the 
apparatus and the house w^iring. 

The high tension transformer is secured in the cabinet 
by means of wooden clamping pieces clearly indicated in 
the drawing. At the end of the first layer of the primary 
winding, a tap of flexible cable is soldered. This will be of 



STAXDAKI) OM'ICE EQUIPMENT 



155 



great service in connection with the impedance in produc- 
ing such effects as the spray or e.ffiuve so desired by many 
'practitioners. The secondary leads from the transformer 
make connection with the ends of a pair of brass rods 
which pass through the partition and directly over the con- 
denser. Across these rods is also secured a safety gaj) 
comprising two pieces of flat brass strip, so arranged that 
the space between their ends is not greater than ^ in. 

The rods should be insulated from the cabinet and the 
partition where they j)ass through the walls by means of 




Fig. 78. — Cabinet, allowing controlling switclies 

hard rubber or composition bushings such as are used in 
incandescent lamp sockets. These rods pass directly 
through the end of the cabinet where they terminate in 
binding posts from which the desired leads may be taken. 

The mounting for the condenser is so arranged that a 
free circulation of air is produced between the sections and 
around them. This is essential if the outfit is to be placed 
in long continued operation. 

The diagram of connections for the ent're outfit is 
given in a separate drawing. 



156 



HIGH FREQUENCY APPARATUS 



Referring to the illustration Fig. 76, we note that all of 
the controlling switches and other parts which require ad- 
justment are located on the cover of the cabinet. The 
standard wireless key at the left is of course placed in 
series with the transformer primary circuit. Fig 78 is an 
enlarged view of this end of the cabinet and it shows 
clearly the arrangements of the controlling switches. Fig. 
79 is an enlargement of the right-hand end of the cabinet 
showing how the rotary and stationary gaps are placed in 
multiple merely by closing the small knife switch. For all 




Fig. 79 — The cabinet, showing the spark gap 

currents at full power or thereabouts the rotary gap is used. 
For the more delicate currents such as that required for 
vacuum tube treatment, the stationary gap is employed. 
By using the full impedance and closing in the stationary 
gap, a spark a fraction of an inch in length and so mild 
that it may be directly applied to the bare skin without any 
pain whatever may be produced. From this we may go 
to the other extreme by opening out the stationary gap, 
starting the rotary, and cutting out all impedance. This 




STANDARD OFFICE EQUIPMENT 



157 



will give us the crashing flame shown in some of the illus- 
trations of the discharge. 

The inductance is placed in series with the primary of 
the oscillation transformer or Tesla coil. This inductance 
consists of 20 turns of No. 10 bare copper wire, wound up- 
on a cardboard drum or cylinder, and with each turn sep- 
arated from its neighbors by a generous space. This wind- 
ing may be done by winding two turns of heavy cord in 
I parallel with the wire, removing the cord after the winding 
is finished. A substantial sliding contact is mounted upon 
the w^ooden coil ends, as shown clearly in the illustration 
Fig. 79. This coil is of great service in obtaining reson- 
ance by tuning the oscillation circuit. 




Fig. 80 — A standard form of Tesla coil 

A form of Tesla coil available in the open market at 
a reasonable price is illustrated in Fig. 80. The construc- 
tion is simple and believing our readers might care to 
build one, we are giving herewith the specifications. The 



158 



HIGH FREQUENCY APPARATUS 



primary consists of six turns of edgewise woun 
strip 10^4 in. inside diameter. This helix is div 



d coppefl 
ided into 




II 



STANDARD OFFICE EQUIPMENT 159 

two parts of three turns each, connected together in the 
middle and mounted upon bakelite posts on either side of 
the central upright piece which is of wood. The secondary 
consists of two cardboard cylinders wound with a single 
layer of No. 24 double cotton covered wire, the w^inding 
covering the entire length of eacb cylinder with the excep- 
tion of an inch at either end. This winding must be very 
thoroughly filled with shellac, layer after layer benig put 
on, and each one being thoroughly dry before the next is 
applied. The secondary coils are joined at the center and 
this point connected with a binding post which leads to the 
ground wire. The outer ends of the winding lead to the 
discharge rods shown in the illustration. 

A complete wiring diagram for the apparatus described 
in this chapter is given in Fig. 81. 



CHAPTER XIV. 
HOT WIRE METER CONSTRUCTION. 

A Hot Wire meter is the most easily and cheaply con- 
structed of all practical electrical measuring devices. It 
may be used either as an ammeter, or in series with a re- 
sistance, as a volt-meter, on direct or alternating current of 
any frequency, and it is the most satisfactory high fre- 
quency current measuring device know^n. 

The principle upon which a hot wire meter operates is 
the expansion of metals when heated. The current passes 
through a long, fine wire ''element,'' which becomes longer 
when heated by the traversing current. The one end of 
this wire element is fixed stationary, while the other end is 
attached to a lever, which acts as an ''indicator." In this 
way the linear expansion of the wire causes a movement 
of the indicator which is proportional to the square of the 
current. 

The instrument here described will give very good re- 
sults and it may be constructed at a minimum cost. Its 
current carrying capacity and sensitivity may be varied by 
changing the cross-sectional area or material of the wire 
used. Platinum alloy wire is generally used on commer- 
cial instruments on account of its high melting point, but 
for experimental work, copper wire will very often answe: 
very well. The higher the resistance and the greater th 
' co-efficient of expansion of the wire, the more sensitive the 
instrument. The higher the conductivity of the wire, th 
greater the current it may carry for a given cross-sectional 

160 



t 



IP 



HOT WIRE METER CONSTRUCTION 



161 



area. The temperature of the wire should not go too high, 
because the higher the temperature of the wire above that 
of the surrounding atmosphere, the greater the loss of heat 
by radiation, and hence the greater ,the inaccuracy of the 
area of the wire must be determined by the current and 
use for which the instrument is intended. It is best to 
instrument. Therefore, the material and cross-sectional 
experiment with several wires to find which is best adapted 
to the purpose. 

The hot wire meter is absolutely ''dead-beat/' /. e, the 
pointer does not fluctuate but comes to an absolute rest 




Fig. 82. — Meter with cover removed 

as soon as it reaches the extent of its travel. To offset this 
pronounced advantage, the instrument is slow to record. 
The hot wire element takes a certain amount of time to 
assume its final temperature and degree of expansion and 
the pointer moves slowly over the scale: If a very fine 
wire is used for the element, the action is hastened and the 
inability of the fine wire to carry any great amount of cur- 



162 



HIGH FREQUENCY APPARATUS 



rent be overcome by using a shunt across the meter term- 
inals. 

Fig. 82 shows the meter in a plan view while Fig. 83 
gives an idea of the movement. The hot wire, 1, is sup- 
ported between two posts, 2, 2, to which the current is 
applied. Attached to the center of the hot wire by means 
of a fine wire hook 3, is a length of silken thread which 
passes in three turns around the spindle of the pivot 4, 
which carries the pointer. This spindle is taken from an 
old alarm clock. From the spindle, the silk passes to the 




ty/re /?ooA 



Fig. 83. — Movement ui the hot wire meter 

end of a coiled spring 5, which is, in turn, held by a low 
post. When the wire element is heated, it lengthens and 
permits the silken thread to be drawn forward by the ten- 
sion of the spring, turning the spindle and moving the 
pointer over the scale at the same time. 

The dimensions given in Fig. 82 are not hard and fast, 
but they are good in that they produce a meter of tested 
efficiency and value. Fig. 84 suggests the method of 
mounting the pivot which carries the pointer. The bridge 



HOT WIRE METER CONSTRUCTION 



163 



IS bent up pi brass strip and the lower bearing is passed 
through the base of the meter. 

The meter may be covered with a suitable case, pre- 
ferably of wood if the instrument is to be used on high 
frequency currents. The mechanism is, of course, covered 
by the case which has an opening cut in it to show the 
scale. The latter should be made as the instrument is 
calibrated. If no standard meter is available for calibra- 
tion, the values may be placed on the scale with fair accur- 
acy if a bank of 16-candlepower carbon lamps is available 
on a 110-volt circuit. Each lamp takes approximately J/^ 




Fig. 84. — The Meter pivot. Showing connections for calibration 

i amp. and by adding one lamp at a time and marking the 
J scale in half ampere divisions, a fairly correct scale will be 
■j the result. Various shunts should be experimented with 
during the first tests in order that the correct one may be 
permanently connected across the binding posts of the 
meter. If the meter is to be read from to 10 amp., a strip 
of German silver ^-in. wide and in about No. 28 to 30 
gauge will be approximately correct. In testing, turn the 
current on in gradually increasing amounts until 10 amp. 



164 



HIGH FREQUENCY APPARATUS 



pass. If the pointer does not describe a full-scale deflec- 
tion, cut a narrow strip from the shunt and try again. 
Continue this paring operation until the needle sweeps to 
the end of the scale when the full amount of current is 
passing. 

For electro-therapeutic purposes, the meter will require 
no heavy shunt as the current is measured in milli-amperes 
or thousandths of an ampere. The most practical scale is 
one reading from to 2000 m.a. (or, to 2 amps.). 

The adjustment for zero is effected by turning the 




Fig. 85. — The meter in its case 

Spindle 4, within the coils of silk thread. This is a damty 
operation but patience is rewarded by success. The thread 
will give some trouble owing to its propensity for absorb- 
ing moisture and changing its length in consequence. The 
only remedy is either to seal the case hermetically or, bet- 
ter still, to use a length of the fine tinsel known as "galva- 
nometer suspension." This may be obtained from a maker 
of hiofh-CTade instruments if the builder is fortunate in 
being near one. The material is exceedingly thin and nar- 
row phosphor bronze strip. 

The hot-wire element should be left just a trifle slack. 



HOT WIRE METER CONSTRUCTION 165 

Under no circumstances should it be taut. Before calibrat- 
ing the instrument, the wire should be ''aged'' by heating 
it to its maximum several times and permitting the pointer 
to come back fully to the zero point. This will lessen- the 
variation from zero. 



CHAPTER XV. 

NOTES FOR THE BEGINNER IN ELECTRO- 
THERAPEUTICS. 

This chapter Is intended, as its name implies, for the 
physician who feels a growing interest in the possibilities 
of electro-therapeutics but who knows very little of the 
subject. The discussion, therefore, opens with a descrip- 
tion of the electrical apparatus in order that the lay reader 
may understand the reference to the various instruments 
in the latter portion of the chapter. 

The Transformer. — The alternating current taken from 
the house lighting circuit at perhaps 110 volts is passed 
through a suitable controlling switch to the primary of the 
transformer. The function of this device is to change the 
intensity or voltage of the current from that suitable for 
lighting lamps to one many hundred times higher. The 
principle of the transformer has already been discussed in 
these columns, but for the benefit of the lay reader it may 
be said to be briefly as follows : When an alternating cur- 
rent is made to flow through a wire, a similar current will 
be produced in a second wire placed beside the first but 
having no connection with it. If the two wires be wound 
into coils and the coils placed side by side, the eflfect is 
greatly enhanced, and if a mass of laminated iron be placed f 
within the openings in the coils the eflfect shows a very 
marked increase. This property of the alternating current 
is known as ^'induction" and the current produced in the 

166 



I 






NOTES FOR THE BEGINNER 167 

second wire is said to be induced by that in the first. The 
voltage of the current induced in the second wire is in 
direct proportion to the ratio between the number of turns 
of wire in the first and second coils. Therefore, if the first 
coil contains one hundred turns and the second coil one 
thousand turns, the voltage induced in the second coil will 
be ten times that applied to the first. Accordingly, let us 
assume that in our transformer there are one hundred turns 
of wire in the first coil or primary, as it is called, and thirty- 
five hundred turns in the second coil or secondary. If we 
impress a voltage of 110 on the primary we shall have a 
voltage of thirty-five times 110 or 3850 volts at the second- 
ary terminals. 

This high voltage makes it necessary to employ highly 
specialized methods of insulating the windings of the trans- 
former for the tendency of the very high potential current 
is to leap through the air for a fraction of an inch or to tear 
its way through even the best of insulators unless they 
present sufficient resistance to its passage. 

We shall next see how this high voltage is applied to 
the operation of the apparatus and what measures are taken 
to safeguard the patient from the dangerous current. 

We have learned that the alternating current, after 
entering the apparatus within the instrument case, is trans- 
formed or stepped up in voltage to a value perhaps hun- 
dreds of times as high as that at which it entered the in- 
strument. This voltage would prove dangerous or fatal 
under certain circumstances if it were applied to the body of 
a patient in its existing state. Before it can be used, there- 
fore, it must be converted to a current of very high fre- 
quency, i. e,, one which changes its direction of flow hun- 
dreds of thousands or perhaps even a million times per sec- 
ond. The astonishing characteristic of such a current is 
that it may be applied to the human body in quantities 



168 HIGH FREQUENCY APPARATUS 

which would prove fatal if the current were of the com- 
mercial frequency. 

The Condenser and Oscillatory Circuit. — Tracing the 
course of the high potential current as it leaves the second- 
ary of the transformer, we find that it passes into a device 
called a condenser. This piece of apparatus consists of a 
number of sheets of tinfoil separated by plates of mica or 
glass. The foil sheets are supplied with lugs projecting 
alternately first from one side and then from the other as 
the foil and mica plates are assembled. The alternate lugs 
are soldered together on each side and to these joints the 
wires from the transformer are fastened. Passing from the 
condenser we find the current flows through the primary of 
another transformer, but one without an iron core, and 
finally across a spark gap and back to the condenser. 

The condenser acts as a reservoir for the current, 
which stores up as a charge on the plates until the tension 
becomes so great that the current leaps across the spark 
gap in a crashing discharge. This discharge is not com- 
posed of a single spark, as appearances would seem to indi- 
cate, but it comprises many separate discharges which 
surge back and forth across the gap with a motion which 
may be likened to that of a swinging pendulum. When 
the energy is finally spent the discharge would naturally 
cease, but during all this time the condenser is again re- 
plenishing its supply from the high voltage terminals of 
the transformer and as soon as one discharge has died 
away, there is another charge ready to take its place. All 
of this happens perhaps in the ten thousandth part of a 
second or less. 

The oscillatory discharge of the condenser across the 
gap sets up a current of very high frequency in the circuit, 
which includes the primary of a second transformer in it, asi 
previously explained. Obviously, therefore, it is only 



NOTES FOR THE BEGINNER 169 

necessary to place within this primary a secondary coil 
having a suitable number of turns of wire in order to obtain 
a high frequency current of any desired potential. There 
is no electrical connection between the two in the, case of 
certain forms of apparatus and, owing to the fact that 
nothing but the current of high frequency would induce 
another current in the secondary of this transformer — due 
to the absence of an iron core — there is no danger whatever 
of the patient receiving a shock of low frequency current 
from the secondary terminals. 

The generation of the high frequency current having 
been explained, the method of adapting it to the various 
electrodes and their uses will next be considered. 

Disregarding for the moment the effects of the various 
frequencies upon the body, we may turn our attention to 
the broad classifications given by the manufacturers of 
apparatus to the currents produced. The classes are in the 
main but three : the Tesla or high potential current, the 
D'Arsonval or medium potential current, and the thermo, 
or as it is sometimes called, the diathermic current which is 
of comparatively low voltage as high frequency currents go. 
In order that the respective uses of the three currents may 
be the more fully understood, it is proposed to treat them 
under their proper headings. 

The High Potential or Tesla Current. — This current 
is that taken from the terminal of the post w^hich tops the 
high frequency apparatus and it is generally applied 
through a vacuum electrode of glass which is held in an in- 
sulated handle of suitable form. The application is quite 
without pain, and, in fact, without much of any sensation 
other than gentle warmth, unless the electrode is lifted 
from the skin in w^hich case the resultant spark is rather 
painful. Therefore, one of the first points for the operator 
to impress upon his mind is the fact that the electrode 



170 HIGH FREQUENCY APPARATUS 



1 



I 



should never be applied or taken from the patient without 
the operator placing his own hand upon the glass to divert ■ 
the current from the patient. The entire success of the 
electro-therapeutic treatment may be said to rest in the 
practitioner first of all inspiring confidence in his patient. 

The most pronounced physiological efifect of the high 
voltage current is shown in the increase of blood supply to 
the part under treatment. This results in an improvement 
in the local nutrition. Other characteristic efforts are an 
increase of heat locally without a rise in the body tem- 
perature, a marked increase in excretion and secretion, and 
a general effect which may be either sedative or stimulat- 
ing accordingly as the current is higher or lower in 
frequency. 

In at least one particular can the vacuum tube appli- 
cation be said to be the direct opposite to the low voltage 
or D'Arsonval treatment. The effect of the vacuum tube 
treatment is to increase the arterial tension when the tube 
is passed up and down the spine, while the auto-condensa- 
tion treatment with the D'Arsonval current is exceedingly 
efficacious in reducing the blood pressure. The pertinent 
fact here is to note that in cases of arteriorsclerosis, the ap- 
plication of the vacuum tube to the spine should never be 
made. However, where the blood pressure is found to be 
normal, this treatment is of great advantage in producing a 
general tonic effect upon the system, particularly if a mod- 
erately low frequency is used. 

In cases of alopecia and other diseases of the scalp and 
skin the vacuum tube treatment has been found invaluable. 
The treatment has received a large amount of publicity 
under the misnomer of ''The Violet Ray,'' and so far has 
this misleading advertising been carried that the treatment 
has frequently been condemned as quack. The violet ray 
part of the proposition is simply a fascinating and perhaps 



NOTES FOR THE BEGINNER 171 

mysterious-sounding trade name which was undoubtedly 
coined as a result of the appearance of the vacuum tube 
when the current is passing. The interior is filled with a 
purplish blue light which has lead to the conception which, 
while it makes no claims definitely, leaves the uninitiated 
under the impression that the treatment is in some way asso- 
ciated with the famous ultra-violet rays of Finsen. The fact 
of the matter is that even though there were an appreciable 
amount of ultra-violet light generated within the tube (as 
is probably the case), the glass walls are practically opaque 
to the ray and its passage to the patient would be stopped. 
However, beyond the mere fact that this slight deception 
has lowered the dignity of the treatment and has made it 
a name almost as common as that of a patent medicine, the 
incident need not concern us. The merit of the high fre- 
quency current properly applied is now definitely estab- 
lished beyond question, and the physician who first learns 
its powers and then uses it honestly is sure to derive ever- 
lasting satisfaction from the treatment. 

The treatment has met with the most encouraging suc- 
cess in the stimulation of the growth of hair on heads 
not hopelessly bald, and the experience of a number of 
prominent workers goes to show that even gray hair may 
be restored to its original color through a perfectly natural 
process. While success has not come in every case, still 
the results are so encouraging that the writer believes he 
is justified in stating that this treatment ofifers a distinct 
opportunity to the scalp specialist who is willing to apply 
himself with the same diligence that he would bestow upon 
some unfamiliar but promising drug. The effects of the 
treatment are cumulative, and in stubborn cases patience 
is necessary, for while the first few^ treatments do not per- 
haps have the desired effect, the cumulative characteristics 
come out after persistent administrations. 



CHAPTER XVI. 

PLANT CULTURE WITH HIGH TENSION 
CURRENT. 

There appears to be a decided scarcity of data cover- 
ing the process of plant culture through the agency of elec- 
tricity. The contributions on the subject have been any- 
thing but specific in nature and this is due, in part, to the 
fact that most of the experimentation has been carried on 
by private investigators w^ho, for various reasons, do not 
seem disposed to make public the results of their research. 
In this country, the greatest progress has probably been 
made by the agricultural departments of several schools 
and colleges, and it is to the excellent bulletins from this 
source that the author is indebted for much of the data 
that led to some private experimentation. While the pres- 
ent discussion is based upon this experimental work, the 
author does not wish to pose as an authority on the subject 
and the remarks herewith are offered in the hope that they 
may lead to some private research on the part of the 
readers. An interchange of ideas and experiences is invited 
and it is felt that such a policy will be conducive to a 
broader presentation of the subject in later editions of this 
book. 

While the art of electroculture is almost wholly in the 
experimental stage, still it may be said that the experiments 
are productive of really practical results and the apparatus 
necessary for their performance is not expensive, providing 
the investigator is content to begin on a small scale. 

172 



HIGH FREQUENCY PLANT CULTURE 173 

There are several methods by which plant life may be 
stimulated with the electric current and, in treating of the 
subject, the author will outline these methods briefly in 
order that the detailed descriptions of the equipment neces- 
sary in each particular case may be made clear. The con- 
struction of the apparatus involved will then be covered 
and it will be optional with the experimenter whether he 
constructs his apparatus or buys certain parts of it ready- 
made from manufacturers. The latter course is desirable 
in many instances as many instruments are rather difficult 
of construction and can be purchased ready for use almost 
as cheaply as they can be made in the home workshop. 

Electroculture Methods. — The methods by means of 

which plant life may be stimulated with the electric current 

I may be divided broadly under two headings : one, in which 

, the rays from an electric lamp are permitted to fall upon 

i the area under cultivation, and the other, that in which a 

I high potential current is sent through a network of wires 

, stretched over the plot of ground. This latter method may 

be further subdivided into two basic headings : One in 

, which a high tension direct or low frequency alternating 

, current is sent through the wires and, the other, that which 

^ employs a high potential, high frequency current. The 

former is simpler and productive of very good results ; the 

latter is the more effective and, in some cases its results 

have been spectacular. 

Merely because the high tension discharge method was 
productive of the most encouraging results in the personal 
experience of the author this method will be discussed first 
of all. It is not claimed that this is the right or even the 
logical method; it simply ''worked'' where others failed 
in the case of one individual investigator who is naturally 
prejudiced thereby. 

The subject under investigation was a bed of lettuce. 



174 



HIGH FREQUENCY APPARATUS 



10 feet wide by 20 feet long. This was situated across a 
yard and SO feet from the companion bed used for purposes 
of comparison. The two beds were boxed in with lumber 
and topsoil was taken from the same load for each; in fact, 
the conditions were as nearly identical as it was possible 
to make them. Four posts were set up at the electrical 
bed, in the corners of the plot as shown in Fig. 86. At a 
distance of 5 feet from the ground, ten wires were spanned 
from cross-arms attached to the poles. The wires were 




Fig. 86. — Showing span of wires to carry the high tension current over a plot of 
ground in which plants are to be cultivated 

carefully insulated with two porcelain cleats in series at 
the end of each wire and a common lead connected the span 
of wires at one end as shown in the illustration. A ground 
connection is made by means of strips of galvanized iron 
''chicken wire" buried in the earth beneath the bed. The 
aerial conductor is brought to a small shed or other shelter 
arranged near the bed under cultivation and in this shed 
the high-tension transformer is placed. The power wires 
from the electric lighting circuit are carried to the trans- 



HIGH FREQUE.XCY PLANT CULTURE 175 

former shed and a switch is conveniently placed both at 
the shed and at the point where the wires leave the house 
or pole. 

Caution Must Be Observed. — The utmost care must be 
used to prevent the possibility of persons coming in con- 
tact with the span of wire over the bed, or, indeed with 
either wire leaving the transformer secondary, as the volt- 
age delivered at this point would produce a dangerous 
shock. To afford a safeguard in this particular, a fence 
should surround the plot and a contact be arranged at the 
gate in such manner that when the gate is opened a bell 
will be caused to ring and this will remind one to turn the 
current off from the transformer before entering the gate. 
This device is not difficult to design and in fact it may con- 
sist of one of the familiar release pushes such as are used 
on door jambs. 

The transformer used by the author delivered a poten- 
tial of 10,000 volts and was rated at Yz k.w. The construc- 
tion was of the closed core variety and the instrument w^as 
immersed in oil to assist in cooling as the runs were from 
8 to 12 hours daily. Such an instrument can be purchased 
for a small sum from manufacturers of wireless telegraph 
apparatus and the experimenter is advised to buy one out- 
right. The necessary details are given, however, so that 
the ambitious worker may try his hand at the job if his 
courage is good. 

Construction of the Apparatus. — The transformer to be 
described is generously proportioned in order to provide 
ample insulation and radiation surface. The constructional 
details for a transformer to operate on the usual 60-cycle, 
110- volt supply are given herewith and in the full-page 
plate the worker will note that data for 25-cycle and 125- 
cycle instruments are given also. The windings for 70, 110 
and 220 volts are appended as well. 



176 



HIGH FREQUENCY APPARATUS 

TRANSFORMER DATA 



125 





|<-2->j< 7I.. 


---A 


A 






1 

i 

1 

1 

1 


Coreforall 

Frequendes 

llOVolk. 









eg 



175 Turns 
No. 12 D.C.C. 



VCLES PRIMARY SECONDARY 

25 700 Turns 64,000 Turns ■ 

No. 14 D.C.C. No. 16 Enamf 

60 350 Turns 32,000 Turns 

No. 12 D.C.C. No. 34 EnanJ 

16,000 Turns " 
No. 34 Enam. 

From the working drawing, the core is seen to be bull 
up from pieces of sheet iron or siHcon steel .014 in. thich 
and 7% in. long by 2 in. wide. This is for the 60-cycle 
transformer. The same general directions apply in the case 
of the other frequencies, therefore the description will b( 
confined to the one only. In all, 460 pieces will be re 
guired. If silicon steel can be obtained from some trans- 
former manufacturer it should by all means be used as it is 
not expensive and its permeability is very much higher 
than that of ordinary sheet iron. The core irons are laid 



HIGH FREQUENCY PLANT CULTURE 



177 



up alternately in piles until each has assumed a thickness 
of 2 inches, after which end pieces are fitted in the spaces 
left in the ends of the piles as shown in Fig. 87. Friction 
tape should be wrapped around the pieces of iron to hold 
them in place. 

The primar}^ coil consists of 350 turns of No. 12 D.C.C. 
magnet wire wound upon a form w^hich will give the open- 
ing in the coil a diameter of 3 inches. The primary may 




3 ; — I 



L 



it 




Figs. 87, 88 and 89. — Details of the high potential transformer 

be wound to a length of 4^ inches and after it has been 
removed from the form it should be carefully taped. 

The secondary is w^ound in 2 section, each containing 
16,000 turns of Xo. 34 enameled wire. These sections also 
have an opening 3 inches in diameter to permit their being 
placed over one leg of the core. The winding is in 80 



178 HIGH FREQUENCY APPARATUS 

layers and has 200 turns to each layer. A strip of oiled 
paper 2 inches wide separates each layer of wire from its 
neighbor and as the 200 turns will occupy a space of ap- 
proximately V/z inches, it is obvious that a space of ^ 
inch will be left as a margin on each side of the paper. 

The starting end of the winding of each section is sol- 
dered to a strip of thin copper ribbon which extends beyond 
the edge of the coil. The finishing end is likewise con- 
nected to a piece of ribbon which should come out on the 
opposite side to that of the starting end. The final layer 
of wire is covered with several thicknesses of the oiled 
paper to afiford mechanical protection. The two sections 
of the secondary are to be wound in such manner as to 
permit the current to flow in the same direction around the 
core when the two starting ends are joined together. 

The primary and secondary are to be assembled upon 
the core as shown in the drawing and the secondary sec- 
tions are insulated from each other and the core by discs of 
heavy fibre. The remaining core irons may then be placed 
in position and the core clamped between wooden pieces 
as the drawing indicates. Pieces of flexible wire are joined 
to the secondary leads and the entire transformer is then 
placed in position in a sheet iron container made oil tight 
Wires leading from the secondary and from the primary 
are brought to suitable terminals in the top of the trans- 
former case. The case is then filled with transformer oil 
until the transformer is well covered. It is believed 
that the drawings will make the details clear and that fur- 
ther description is unnecessary. 

It is, of course, understood that the line wires supply 
ing the alternating current of sixty cycles at 110 volts ar. 
connected with the primary terminals while the secondary 
terminals deliver a current at approximately 10,000 volts tc 



HIGH FREQUEXXY PLANT CULTURE 179 

the span of wires over the plants to be cultivated ; that is 
to say, one secondary w^ire leads to the overhead w^ires 
v^hile the other secondary terminal is connected with the 
ground. 

Actual Results Obtained. — A most interesting report 
on electroculture experiments was made recently by ]\Ir. T. 
C. Martin at a convention of electrical men and from this 
'report it may be deduced that, of all the processes by 
-means of which plant life may be stimulated, the one em- 
^ploying the high frequency current as it fundamental prin- 
ciple is the most successful by far. 

The experiments mentioned by Mr. ]\Iartin were car- 
ried out at the Moraine Farm, a few miles south of Day- 
^ton, Ohio, and located in the celebrated ^Nliami River Val- 
ley. The experiments were promoted by F. M. Tait, 
formerly president of the National Electric Lamp Associa- 
tion, and were in the immediate charge of Dr. Herbert G. 
Dorsey, whose work in this line has long been worthy of 
Unote. 

''In preliminary tests, according to Mr. ]\Iartin's re- 
jport,'' says the Philadelphia Inquirer^ ''small plots were 
:marked ofif for exposure to different kinds of electrification. 
f'To insure that the soil of one plot was not better than that 
jof another, top earth was collected, mixed and sifted and 
jthen was laid to the uniform depth of seven inches over 
.^he entire area.'' To quote further : 

i; "In the soil of Plot No. 1 was buried a wire screen. 
■Over the plot was a network of wire, stretched about 15 
'inches from the ground. Connecting the network above 
the ground and the screen below were several wire an- 
tenna. The screen was connected to one terminal of a 
ijTesla coil and the network to the other. A transformer 
stepped a 110- volt alternating current up to 5,000 volts, 
charging a condenser of tin-foil and glass plates, which dis- 



180 HIGH FREQUENCY APPARATUS 

charged through a primary of the coil. About 130 watts 
were operated for an hour each morning and evening. 

'Tlot No. 2 was illuminated by a 100-watt tungsten 
lamp with a ruby bulb. The light was turned on for three 
hours daily beginning at sundown. Plot No. 3 was illum- 
inated the same way, except that a mercury vapor lamp 
was used. No. 4 had ho artificial stimulation of any kind, 
being intended as a comparison between electrically ex- 
cited plant growth and that of natural conditions. 

'^In Plot No. 5 was buried a wire network connected 
to the terminal of a 110-volt direct current. The positive 
terminal was attached to a small sprinkling can with a car- 
bon electrode in its center. The can being filled, the water 
was subjected to electrolysis for several minutes. The plot 
was then sprinkled from the can, the theory being that the 
current might flow from the can, through the streams of 
water to the soil. 

"Plots Nos. 6 and 7 were sub-divided into four indi- 
vidual boxes, two feet square, separated by porcelain in- 
sulators and arranged with carbon electrodes at each end. 
To these electrodes were applied both direct and alternat- 
ing currents. 

''After radish and lettuce seed had been planted and 
germination had begun, the various methods of electrifica- 
tion were tried with extreme care. The result of the ex- 
periments diowed that the plants in Plot No. 1 grew in 
every instance far more rapidly than those in the other 
beds and more than double the normal growth as shown 
in the unelectrified bed.'' 

The comparative results obtained with the various 
processes may be noted in the table which follows, and it is 
interesting to observe that the high frequency current fron^ 
the Tesla coil takes the lead from the standpoint of weigh^ 



HIGH FREQUENCY PLANT CULTURE 181 

of the edible portion of both radishes and lettuce grown 
under its influence: 

Plot 1 Plot 2 Plot 3 Plot 4 Plot 5 
Radishes (ten plants selected at Tesla 

random) : Coil 

Total plant weight, grams 265.70 

Edible portion, grams 139.50 

Edible portion, per cent 51.15 

Tops and leaves, grams 120.50 

Tops and leaves, per cent 43.35 

Roots, grams 9.30 

Roots, per cent 3.50 

Lettuce (ten plants selected at 

random) 67.00 

Edible portion, grams 60.70 

Edible portion, per cent 90.59 

Roots, grams 6.30 

Roots, per cent 9.41 



Ruby 


Mercury 


Nor- 


Elec. 


Light 


V'apor 


mal 


Spkg. 


137.80 


109.50 


180.00 


78.50 


57.40 


40.90 


79.40 


31.00 


41.65 


37.34 


44.11 


39.49 


75.70 


65.90 


95.00 


41.50 


54.92 


60.18 


52.77 


55.66 


4.70 


3.20 


5.60 


6.00 


3.43 


2.48 


3.12 


4.85 


52.60 


56.60 


46.10 


31.30 


57.30 


50.20 


41.80 


28.20 


89.92 


88.85 


90.67 


92.10 


5.30 


6.30 


4.30 


3.10 


10.08 


11.15 


9.33 


7.99 



CHAPTER XVII. 
HIGH FREQUENCY PLANT CULTURE. 

High Frequency Cultivation. — The successful genera- 
tion of an electric current at high potential and high fre- 
quency offers a problem not easy of solution, particularly 
if this current is to be put to practical use for long-con- 
tinued periods of time. While there are several methods 
of producing the current, only one will be considered here 
as the others are deemed impractical for amateur use. 

The generator to be described is designed for hard 
duty. The complete apparatus comprises a transformer, 
condenser, spark gap and an oscillation transformer. In 
the construction of the apparatus, a fairly complete electri- 
cal knowledge is essential. The high-voltage transformer 
must be carefully made and properly insulated, while the 
accessory apparatus requires not a little mechanical skill 
for its successful completion. Once constructed, however, 
the operation of the outfit is a simple matter and quite 
within reach of the average fruit or vegetable grower. 

In order to simplify the explanation-, the description of 
the transformer will be divided into sections, each bearing 
the appropriate heading. 

In accordance with the inevitable policy of this book, 
the data for transformers of various frequencies are given 
in the full-page plate appended. The description is for 
the 60-cycle instrument, and, as the construction of the 
others is the same, a repetition would be superfluous. 

Construction of the Core. — The core is composed of 
thin sheet iron or preferably silicon steel which may be 

182 



HIGH FREQUENCY PLANT CULTURE 183 

obtained from transformer manufacturers. The sheet metal 
is to be cut into strips according to the specifications given 
in Fig. 90. The 2 by 6 inch strips are divided into two 
piles of 130 pieces each and these strips are assembled al- 
ternately with the ends overlapping two inches. The Ij^ 
by 6 inch strips are next divided into four piles of twenty 
each and these are assembled alternately also. These 
packs are then to be placed above and below the assembled 
piles as shown in Fig. 92 to break the sharp corners. The 
piles are then wound tightly with tape and fin?.lly covered 
with several layers of press-board, preparatory to winding 
the primary and secondary. 

Winding the Primary and Secondary. — The primary 

! is wound on one leg of the core and the secondary on the 

I other. The two cores are then joined in a complete mag- 

I netic circuit by the end yokes as shown in Fig. 1. The 

primary winding consists of 125 turns of No. 10 D.C.C. 

> copper magnet wire wound 25 turns per layer and five lay- 

( ers deep. Between each two layers of wire, a turn of 

I press-board should be taken. The first and last turns of 

j, wire are held in place with loops of strong tape placed un- 

; der the winding and drawn tight after the turns are in 

; place. No shellac or other paint is used on the winding as 

the coils are to be immersed in oil when the transformer is 

completed. 

The secondary winding is in two sections, each con- 
I taining 4200 turns of No. 28 enameled magnet wire, making 
' 8400 turns in all. The wire is wound in layers about an 
: inch wide and separated by a double thickness of oiled 
' paper between each tw^o layers of wire. The paper should 
j be 1^ inches wide In Fig. 95 is shown the method of 
' clamping the core leg in the lathe for winding. 
; Before starting the winding, a strip of thin copper rib- 

j bon is cemented to the insulation as shown in Fig. 96 to 



184 



HIGH FREQUENCY APPARATUS 



1 



provide the connection between the two halves of the sec- 
ondary. A strip of paper is placed over the ribbon and the 
winding started after the end of the wire has been soldered 
to the ribbon. When the first section of the secondary has 
been completed, the finishing end of the wire is sol- 
dered to a piece of ribbon, a few turns of paper taken over 
the final layer of wire, and the core leg removed from th^l 
lathe. The fibre shield which separates the two secondary" 
sections is then slipped in place and the core replaced in 
gether by means of the copper strip. 



Ccrcrequ/rci oo p/ece^ ff'6'. lio p/ece^ z''6'. ^4op/eCiM t''7' 
^il/con ^fea .on' f/}/ca. f ^ 



-jF,q.l. 



2 




7--4*2:J 



J One /eg ojjemoiec/ L eg mf/) primary 
and foped ready for tvfr}d//?g m place 
tv/ncf/ng. 



dhcA. 




n'dre^h/e/d. 




Cover tv/fh j/ouero of/ea 
paper /J'lv/de 



^ccfionA A 



iecfton through CO// 

and core 




Tope</ J 
[rxfd forced /nfo bhcJt. 



Onejide oftvinding 
comp/efed 



( J /oyer J press board. 
^Locaf/or) off/bre Jh/e/d 
^from ree/ 




Core reversed 
/r?/aw 



^Jh/e/a 



I 



Figs. 90 to 98 inclusive — Details of the magnetic leakage transforme 

the reverse direction ; that is, the core is turned end-for-en 
in replacing it to make the blank portion of the core tak 
the place of the wound section. The second half of the 
winding is then started by soldering the wire to the cop- 
per strip as before. Assuming that the lathe is turned al- 
ways in the same direction, the act of reversing the core in- 
sures that the direction of the winding shall be continuous 
in both sections, with their starting ends connected to- 
Assembling and Mounting. — The secondary finished, 
the two legs containing the windings may be stood on end 



lilGil FREQUE.XCY PLANT CULTURE 



185 



and the remaining core strips inter-leaved in place to com- 
plete the magnetic circuit. 

The reader is referred to Figs. 99 and 100, for the 
method of mounting the transformer. The core is gripped 
between clamping strips of hard wood and bolted to a base 
of the same material. The primary and secondary 
leads are conducted to upright pillars of hard rubber hav- 
ing a brass rod running through the centre. 




s^sssa 




P/on of confo/nen 
/fo/e^ /n cover for roc/^ fo pass 




Section 53 



Figs. 99 to 102 inclusive. — The transformer assembled and details of its container 

The transformer is placed in a container of wood, lined 
with zinc as shown in Figs. 101 and 102, which give the 



186 



HIGH FREQUENCY APPARATUS 



proper dimensions. In the cover of the container are bored 
four holes to pass the terminal rods. 

When the transformer has been placed in the case, the 
latter is filled with transformer oil to within an inch of the 
top and the cover fastened down with screws. The addi- 
tion of substantial handles at the ends of the container 
completes the work on this portion of the apparatus. 

Construction of the Condenser. — In the design of the 
condenser for our purposes, one or two primary requisites 
have constantly been borne in mind. The condenser is 




Fig. 103. — The condenser complete showing method of connection 

subjected to practically continuous use for several hours 
at a time and it is obviously essential that ample radiation 
surface be provided in order that the plates may remain 
cool. Coupled with this highly important point may be 
mentioned the importance of eliminating all corona or 
brush leakage around the edges of the tinfoil plates. 
These requirements are ordinarily met with in an oil im- 
mersed condenser, but the latter, to be efficient, should em- 
ploy only oil as its dielectric and such a condenser presents 



HIGH FREQUENCY PLANT CULTURE 187 

constructional difficulties not easily conquered by the ama- 
teur workman. As the next best solution of the problem, 
the design for a glass plate condenser of large heat-radiat- 
ing surface and of substantial construction is offered in this 
chapter. 

For its construction the condenser will require 120 
plates of glass 8 by 10 inches of the kind used for photo- 
graphic negatives. Old plates of the latter sort may be 
purchased cheaply from nearly any photographer and they 
serve the purpose admirably. The first step is to remove 
the emulsion coating on each plate by soaking it in hot 
water and scraping with a putty knife. The plates are 
then to be dried thoroughly and divided into four piles of 
30 plates each. The complete condenser consists of four 
units, of 30 plates each, connected in series multiple as 
shown in Fig. 103, and in order to make the description 
clearer the steps in the construction will be given for but 
one of the four units, which are alike in every particular. 

A good grade of varnish gold size is procured and 
placed on the work-table with a good soft brush about an 
inch in width. Tinfoil of the grade used by florists may be 
^procured in pound packages containing four or five strips 
of foil six inches wide and perhaps 48 inches long. The 
foil is to be cut up into pieces 6 by 8 inches in size, neatly 
flattened and separated ready to be applied to the glass 
plates, which should be arranged in a pile on the table. 
A plate is removed from the pile and given a quick, thin 
coating of the varnish (which dries in twenty minutes in 
the open air) and a sheet of foil immediately laid upon it, 
care being taken to see that the foil is accurately centered 
on the plate. The foil may be forced into smooth and close 
contact with the glass with the aid of a wad of cotton 
placed within a piece of soft cloth to make a sort of pounce 
or dauber. Starting at the center of the foil sheet and 



188 



HIGH FREQUENCY APPARATUS 



carrying the rubbing process toward the edges with a cir-l 
cular motion, the workman will be able to force the foil 
into what is practically absolute contact with the glass, and 
at the same time cause the surplus of varnish to exude 
from the edges. 

The plate is then turned and coated on the other side 
in exactly the same manner; the process is repeated with 
each of the thirty plates in each of the four units until the 
120 plates have been coated. The lot may then be laid 
aside to dry in a warm room for several days. When this 
has been accomplished, each plate is to have its edges 







rti 


p 



Fig. 104. — One section of condenser mounted in its case 

dipped into melted beeswax to a depth of 1^ inches in 
order that the edge of the tinfoil on both sides may be 
thoroughly coated with the wax. This will quite prevent 
the corona or brush losses so frequently noted with glass 
plate condensers. 

The rack in which the plates are to be mounted may 
next claim our attention. Its construction may be noted 
in Fig. 104, which gives a perspective view of the complete 
unit. The reader will see that the support comprises a 
baseboard and cover of wood separated by two end pieces. 
The plates slide in grooves formed by ^-inch square strips 



HIGH FREQUENCY PLANT CULTURE 



189 



of wood nailed to the base and cover. A bar of J/g-inch 
by 1 inch copper runs across from one end piece to the 
other on either side and affords a means of connecting the 
many plates in multiple. This connection is accomplished 
by means of the special contact leads shown in Fig. 105. 
These leads are merely pieces of lamp cord tipped at one 
end with a lug and at the other with a contact made from 
a piece of spring brass ribbon bent into the shape shown 
in the drawing. The object of the contact is to establish 




Fig. 105. — Spring connector and cord for condenser 

connection between both plates of tinfoil when the spring 
is inserted. 

In making the connections to the bars on either side, 
the contacts are alternated in order that the plates may all 
be in multiple. That is, referring to Fig. 104, in starting to 
insert the contacts, on the one side the first contact spring 
is inserted between the first and second plate ; on the other 
side the contact would be between the second and third ; 
returning to the nearer side, the second contact is inserted 
between the third and fourth plates, and so on until all 
have been put in place. The contact with the first and last 
coatings are of course made by inserting the clip between 
the tinfoil and the wooden end piece, placing a small sheet 



190 



HIGH FREQUENCY APPARATUS 



of glass between the spring and the wood to prevent the 
metal coming into contact with the wood. 

When the four units have been made as described, 
they are to be connected up as shown in Fig. 103, the con- 
necting leads being strips of copper ribbon. The setting 
up will receive due attention when the rest of the apparatus 
has been described. A 

Construction of the Spark Gap.— Perhaps no one por- 
tion of the high frequency apparatus is more likely to give 
trouble and to require frequent attention than is the spark 





Fig. 106. — Self-cooling spark gap 

gap across which the condenser discharges. The discharge 
is accompanied by heating effects which are in themselves" 
troublesome, and while the ordinary stationary form of. 
gap may give satisfactory service for a time at least, stil^ 
its successful operation is hindered as the sparking surfaces 
become heated and pitted. The gap to be described has 




HIGH FREQUENCY PLANT CULTURE 



191 



proved its value in actual practice and, while it may appear 
to be unnecessarily complex in design, still the many points 
of advantage are only brought out through the construc- 
tion of a substantial and more or less massive affair. 

With reference to the side elevation and plan views 



f steel j/joff ej'tong - 



do5se<i furnecf up ^ 
from drojj rod " 



Bi. 




Defofl of rotor 
on(f shoff 



Oefo/t of brush <if)o/cfer 



Fig. 107. — Details of the spark gap 

arranged to rotate in opposite directions at a fairly rapid 
rate of speed. The rotation serves the double purpose of 
always presenting a fresh sparking surface, and therefore 
a cool one, to the point of discharge, and in establishing a 
strong current of air directly upward and between the 
sparking surfaces, due to the surface friction of the periph- 
ery of the discs. The effect of this current of air is to as- 
sist in the wiping out of any arc which may form during 
the discharge. 

The discs are mounted upon a substantial framework 



I 



i 



192 HIGH FREQUENCY APPARATUS 

and base of dry wood which has been painted with or pref- 
erably boiled in paraffin wax. The discs are mounted upon 
shafts of J^-inch steel and secured to the latter by means 
of brass bosses turned up and drilled to a snug fit on the 
shaft. When the final assembling has been done the bosses 
are pinned to the shaft and to the disc, thus insuring th^ 
permanency of the construction. The final operation is 
to take a finishing cut ofif the periphery of each disc with 
the shaft held between centers in the lathe. 

The details of the bearings are given in the enlarged 
drawings, Feg. 107. The reader will note that the bearin 
proper is a journal of brass tubing reamed to fit the shaf 
nicely. The bearing support is a casting with a hole cored 
through it to take the journal. Slots in the feet of the 
bearings permit the distance between the discs to be varied, 

When the various parts have been finished, the bear- 
ings are located on the framework as shown in the plan 
drawing and the journals slipped over the shafts. A piecci 
of cardboard is then forced over each end of each journal 
after the latter has been propped up inside the bearing. 
with bits of wood. Melted lead is then poured into thcf 
opening at the top of the bearing and when cold it will 
hold the journals in perfect alignment with the shaft. The 
bearings may then be removed and a small hole drilled 
down through the lead and brass to afford a passage for 
oil to the shaft. The addition of an oil cup stuffed with 
a wick completes the bearings, which may be replaced on 
the frame. 

The shafts are belted together with rubber belting 
crossed to make the discs turn in opposite directions. The 
driving is accomplished by means of an electric motor 
belted to a pulley on one shaft. 

The current is conducted to the discs through wire or 
-gauze brushes bearing upon the smooth bosses, as shown 



HIGH FREQUENCY PLANT CULTURE 193 

in the plan view in Fig. 106. The details of the brush 
holder are to be seen in Fig. 107. 

The discs should rotate freely and quietly when the 
motor is started. If the oil cups are properly fitted, the 
gap should be capable of an all-day run without trouble 
developing. The adjustment of the gap will be considered 
in due time, when the instructions are given for the oper- 
ation of the completed apparatus. 

The Oscillation Transformer.' — The reader has been 
told of the construction of the transformer which steps the 
commercial lighting current up to a potential of several 
thousand volts, the condenser w^hich stores up this high 
voltage, and the spark gap or discharger across which 
leaps the stored-up current in the condenser. The dis- 
charge of the condenser across the gap sets up electric 
oscillations or, as it is termed, a high frequency current. 
In order that this current may be rendered suitable for the 
purposes of electro-culture, however, its potential must be 
raised to a very much higher degree and the object will be 
to explain the construction of the special type of trans- 
former or coil employed in the process of stepping up the 
already high potential, high frequency current. 

The high frequency transformer differs from the type 
used for the conversion of low^ frequency or commercial 
^currents in that it has no core of iron and the turns in its 
jprimary and secondary are numbered in tens and hundreds, 
"respectively, instead of in hundreds and thousands, as is 
the case with the transformer used for lighting and power 
jwork. Furthermore, on account of the extremely high 
potentials induced in the oscillation transformer, the insu- 
lation problem must be treated in a somewhat radical man- 
ner. This problem is not, however, so difficult of solution 
s it* might seem. The coil may be of generous propor- 



r 



194 



HIGH FREQUENCY APPARATUS 



tions, since close coupling of the primary and secondary 
winding is not essential, and the permissible air space 
affords a most effective insulator. While the efficiency of j 
oil insulation in cases similar to the present one is not' 
questioned for one moment, still the air insulation, if prop- 
erly carried out, offers exceptional advantages over all 
other forms wherein the windings are hidden from vie^^ 
and are inaccessible. The latter method has accordingl} 
been selected. 




Fig. 108. — The oscillation transformer complete 

The transformer consists essentially of a primary 
winding of eight turns of copper strip placed at the base of 
a cylinder around which is wound the secondary of 300 
turns of No. 30 D.C.C. copper magnet wire in a single 
layer. The starting point of the primary, as well as that of 
the secondary, is connected to a stud of metal which passes 
through the base of the instrument for ground connection. 
The primary of the coil is connected in the circuit of the 



HIGH FREQUENCY PLANT CULTURE 



195 



condenser and spark gap in order that the oscillations may 
pass through the copper strip and thus induce a high fre- 
quency current of higher voltage in the secondary winding. 
The general appearance of the completed coil is shown in 
the illustrations, Fig. 108, and in Fig. 109 the reader will 
find details of the parts from which it is constructed, to- 
gether with the dimensions of the various pieces. 

The secondary cylinder is of cardboard and made ex- 
pressly for the purpose. In designing the coil, the writer 




iregcf 



~^. 






I Base of tvhifewood tregcf 

IL 



!3 heads for cyf/nder of 
whifetvood 



' cm 
hiretVi 

f/i'^iv a/fjfdecp 
- - lorr for pnr, 



~ 6c ft rudder feet — — -"■*^ 

fi'iiTiory dip copper y^ pf^ 
Pnmory a turns ofed^njse '" 






Overtieod"^ 




lermmof post of 
d/ocA: f/dre rre^'cf 



^ Cro'jnd 
Diogrcm cf ccnnecf/on 



I reqd 



Fig. 109. — Details of the oscillation transformer 

I has purposely chosen, wherever practicable, dimensions 

' which correspond Avith the standard sizes of the parts now 

] obtainable through electrical manufacturers. ^Accordingly, 

I the cylinder has b.een made eight inches in diameter and 

1 13 inches long. The wall is about one-fourth inch thick. 

Into each end of the cardboard cylinder is fitted tightly a 

i head turned up from whitewood and soaked for an hour 

in melted paraffin. The heads are drilled for the terminal 

post and the brass stud, respectively. The details of the 



196 HIGH FREQUENCY APPARATUS 

terminal are given in Fig. 109 but the stud has been 
omitted, since its construction is obvious. The next opera- 
tion is to treat the cardboard cyHnder to three coats of 
shellac, making certain that each coat is bone-dry before 
applying the next and baking the cylinder after each coat in 
a moderately warm oven. 

With the third coat of shellac quite dry, the cylinder 
may be mounted in the lathe between centers, a slender 
screw driven into the wooden head and catching a slot in 
the faceplate to afford a means of driving. The lathe 
should then be speeded up and the surface of the cylinder 
carefully gone over with the finest sandpaper to remove 
the inevitable irregularities caused by particles of dust and 
dirt. On no account must emery paper or cloth be used 
and the lathe bed must be scrupulously clean while the 
cylinder is being handled, as the least trace of metal chip 
or dust under the winding would be fatal to good results. 
The surface of the cylinder having been carefully 
smoothed over, the lathe may be prepared for the wind- 
ing. The gears are set to cut 24 threads per inch and the 
winding of No. 30 D.C.C. wire is started one-fourth inch 
from the end. In starting, the wire should be passed 
through a small hole in the cylinder and the hole im- 
mediately plugged with a bit of wood covered with wet 
shellac. This will prevent the winding from coming loose 
during subsequent handling. The lathe should be turned 
slowly and backward, and the wire fed through a guide 
held in the tool post. When the finishing turn, the 300th, 
is in place, the final end of wire may be passed through 
the cylinder and secured as was the starting end. 

While the coil is still in the lathe, the winding should 
be coated with shellac applied in a thick solution and with 
a soft brush, the greatest of care being taken to see that 
the fluid soaks Vv^ell into the turns and between them and 



HIGH FREQUENCY PLANT CULTURE . 197 

also that no air bubbles or particles of dirt are permitted 
to remain. When the first coat has dried for an hour or 
more, the cylinder may be carefully removed and placed 
in the oven, wherein the temperature should not be over 
150 degrees F. The baking may continue for a few hours 
and the second coat applied after the coil has been put 
back in the lathe. The builder is strongly advised to do 
all of the painting in the lathe, as the examination and 
turning of the cylinder is greatly facilitated thereby. The 
third coat may be the final one and it should be dried as 
thoroughly as the first and second. 

The secondary finished, the w^ooden heads may be re- 
moved and connection made with the terminal and base 
studs. This is easily accomplished if the ends of the wire 
are left long and passed through the holes in the heads 
with the studs fitting loosely. When the heads are re- 
placed, the wires may be drawn taut and the nuts of the 
studs turned up to grip the bare wire. The heads may 
then be secured in place by plugging w4th wood dipped in 
shellac, the small holes drilled around both top and bot- 
tom of the cylinder. 

The base of the instrument is simple in construction, 
as is readily seen in the drawing. The method of support- 
ing the primary strip, as well as the nature of the latter, 
will, however, bear some explanation. The copper strip is 
^-inch wide and iV"i^ch thick and is wound edgewise into 
a helix having an internal diameter of 10j4 inches. This 
helix material is also to be obtained in the size given and it 
can be purchased far more cheaply than it can be formed 
up by the amateur workman unless he has the necessary 
equipment for the bending operation. As this device is 
quite complicated, the space necessary for its description 
will not be taken here. The problem is to bend the thin 
strip edgewise and prevent it from buckling. 



I 



198 HIGH FREQUENCY APPARATUS 

Assuming that the builder has procured the helix 
material, eight complete turns of which are required, the 
attention may be directed to the posts which support the 
helix on the base and at the lower end of the secondary 
cylinder. From the detailed drawing in Fig. 109 the reader 
will note that four posts of black fibre rod, 2^ inches high 
and one inch in diameter, are given a series of saw cuts to 
a depth of three-eighth inch. Eight cuts will be required 
in each post to take the eight turns of primary strip. The 
cuts may be made with two blades of a hacksaw placed 
side by side to give the required thickness or, what is by 
far the better method, the cuts may be taken in a milling 
machine if one is available. The posts are located on the 
baseboard and secured with short machine screws tapped 
into the fibre. Care should be taken to see that the screws 
do not pass into the posts beyond the bottom turn of the 
primary. 

The assembly of the parts is clearly shown in Fig. 110 
and it is believed that no further comment is necessary 
other than to say that the bottom turn of the primary is 
connected with the ground stud, as shown in the diagram 
of connections. I 

Installation of the Apparatus. — We have seen how the* 
various instruments comprising the high frequency current 
generator are built in order that we may have available a 
steady supply of high potential current, oscillating at a fre- 
quency of approximately 100,000 cycles per second. It is 
this high potential, high frequency current that we shall 
employ in the electrification of our plot of ground, and the 
object of the present article is to point out how the various 
instruments of the outfit are connected and combined to 
produce the current. 

The entire outfit should be housed in a perfectly 
weather-tight shed. The construction of the building may 



HIGH FREQUENXY PLANT CULTURE ^ 199 

be comparatively crude, if the precaution is taken to care- 
fully seal all cracks and crevices, not only in the walls, but 
around the door as w^ell. In rainy weather, or even when 
the humidity of the air is high, the inside of the shed should 
be kept dry and warm by means of a small oil stove. 
Dampness is positively fatal to the successful operation of 
the apparatus if it is permitted to strike in for any length 
of time. 

The shed should contain a substantial wooden table 
along the rear wall facing the door, and upon this table the 
apparatus is arranged in the order shown in Fig. 110. 

The floor of the shed should be at least one foot 
above ground and an open air space should be left beneath 
in order to frustrate dampness so far as is possible. A 
simple and good construction is to build the shed around 
four substantial corner posts, starting the walls a foot 
above the ground. The roof should have a generous slant 
to shed the rain. 

With reference to the first drawing, the apparatus is 
arranged in the following order, left to right : Transformer, 
spark gap, condenser and oscillation transformer. Upon 
the wall to the left is secured the main switch, which 
should incorporate a cut-out fitted with 15 ampere plug 
fuses. To this switch from the outside of the shed, lead 
the line wires, which are to be supplied with a 110- volt, 60- 
cycle alternating current, preferably from the local central 
station. 

Beside the main switch, the switch for the spark gap 
motor should be located. The primary terminals of the 
transformer are to be connected with the main switch, as 
shown in the wiring diagram below, which also shows the 
connections for the remainder of the apparatus. From the 
secondary terminals of the transformer pieces of No. 14 
rubber-covered wire lead to the terminals of the spark gap. 



200 



HIGH FREQUENCY APPARATUS 




HIGH FREQUENCY PLANT CULTURE 



201 



From one terminal of the spark gap a piece of stranded 
cable, composed of 100 strands of about Xo. 24 insulated 
magnet wire, runs to one terminal of the condenser. From 
the other terminal of the condenser, a piece of the stranded 
cable leads to the movable clip on the primary of the 
oscillation transformer. The second terminal of the spark 



To Overhead Wires 



^VO Volts -60 Cycles A.C. 



Spark Gap 



Condenser 



Oscillation 




Transformer-' 



Ground -=^ 
Fig. 111. — Diagram of connections for the apparatus 

gap is connected by cable to the ground connection of the 
oscillation transformer and this in turn to a series of wires 
buried in the ground beneath the plot to be cultivated. 

The high-potential, high-frequency terminal of the 
oscillation transformer connects with a piece of light cop- 
per rod, which extends upward and out of the side of the 
building, through a hole cut in the center of a pane of 
glass. This glass window should be at least 18 inches 
square and shaded on the outside of the building with a 
contrivance resembling an awning, in order that the surface 
of the glass may be kept as nearly as possible in wet 
weather. The copper rod passing through the glass is 
tipped with a connector to which the overhead wires of the 
plot are secured. 

Wiring the Plot. — The high frequency current pro- 
duced by the apparatus described is administered to the plot 
ground under cultivation through the agency of an over- 



202 



HIGH FREQUENCY APPARATUS 



1 



head network of copper wires and a ground connection con- 
sisting of strands of wire buried in the earth of the plot. 
The transformer house is preferably located at one end of 
the plot in order that the high frequency current may be 
carried to the area under cultivation by the shortest pos- 
sible route. This is highly desirable, as an appreciable loss 
would be sustained in a long transmission line. 

The equipment recently described is of sufficient power 
to cultivate a plot of ground embracing 5,000 square feet, 
and, in the case under the writer's observation, the plot 
measured 50 feet in width by 100 feet in length. The 



To transformer 



Unit N'J 
dop/afed 



umtfTi' 

30 platen 



unit N^3 
jop/afei 



un/r/v'4 
jop/o/ej 




m To tron^former 



One p/ote of condenser q''io' glojj coated 
both J Ides witti tinroii to within /'of edge. 

Dip edges ir\ melted t?ecs\^aA to a depth 

of if all around. 



f^eft^odof Connecting 
Condenser 



Fig. 112. — Showing how four units of condensers are connected 

ground wires, three in number, were run the entire length 
of the plot and spaced ten feet apart. Crossing these wires 
at ten-foot intervals were ten bridging wires arranged as 
shown in the illustration and soldered at each joint. In 
all cases the wire was of No. 16 bare copper. At the end 
of the plot nearest the transformer house, the ground wires 
were brought together in a rat-tail and connected with the 
ground lead of the apparatus. 

The overhead network presents a more difficult 
problem. In the experimental plot ten wires spaced five 
feet apart ran the entire length of the plot and were sup- 



FURTHER NOTES OX PLANT CULTURE 203 

ported at either end upon high-tension insulators held by 
posts which were of such a height that the}^ suspended the 
wires seven feet above ground. At twenty-foot intervals 
on either side of the plot, additional posts w^ere located and 
cross wires between each two of these posts completed the 
network and at the same time relieved the strain upon the 
slender wires running the length of the plot. As in the 
case of the ground network, all joints were soldered. The 
overhead connection is in the nature of a continuation of 
each of the long wires to form a rat-tail, grouping all of 
the wires where they are connected with the high-tension 
lead passing through the glass window of the transformer 
house. 

The insulators on the posts may be of the conventional 
glass high-tension type or they may be cobbled up by 
grouping a series of porcelain cleats as suggested in the 
appended illustration. The best of insulation is none too 
good, particularly in damp weather, as the high-tension 
current leaks badly in its effort to find its way to the 
ground. 

The actual time of treatment will naturally rest with 
the individual investigator. From one to four hours, both 
night and morning, is a fair dosage, and noteworthy results 
have been obtained with this average treatment. The 

I plants or vegetables under cultivation should be planted in 
duplicate in a neighboring bed in order that comparisons 
may be made at frequent intervals. In order to put the 
experiments on a practical footing, the notes taken during 
treatment and subsequently should include data on the 

I weight, amount of foliage, percentage of edible portion, 

I quality of the latter, time required to bring plants to 
maturity, etc. These notes wdll be useful not only to the 
individual investigator, but to the w^orld at large. 



CHAPTER XVIII. 
FURTHER NOTES ON PLANT CULTURE. 



I 



"|i 



Every radio telegraphic transmitter, large or small, 
amateur or professional, is a potential cultivator of plant 
life. Through a simple conversion of the oscillation trans- 
former, the apparatus to be found in the possession of 
every licensed radio amateur can be made to perform this 
practical service in connection v^ith the so-called ''kitche 
gardens'' springing up all over the country. 

Following this line of reasoning, Mr. F. F. Pickslay, 
an ardent experimentalist of Mamaroneck, N. Y., called at 
the offices of the author and made known his plans, which 
wxre formulated largely as a natural result of the order to 
dismantle all radio stations in 1917. 

The entire stretch of ground planted measured 38 feet 
front by 110 feet deep. This plot w^as divided into two 
parts, one of which was electrified, and the other was with- 
out current, for purposes of checking results obtained. 
The Distributing System 

The system for distribution of the high-tension, higJ 
frequency current was simple. It comprised essentially 
net-work of copper wire suspended above the garden at 
distance of some 8 ft. from the ground, and a series of 
copper wires placed in shallow trenches beneath the ground. 

In the case of our garden, the placing of the ground 
wires was a simple matter. The plot was first plowed, then 
raked, and finally the ground wires were placed in furrows 

204 



Jl 



FURTHER NOTES OX PLAXT CULTURE 



205 



produced by means of a hand plow or cultivator of the 
kind sold in nearly every country hardware store. The 
ground wires, nine in number, were bridged at either end 



To High Tension 



Jerminab 




\<^--20'---'^--20'-->f^ -20'--^ 



IQQ 

Transformer ^'^^ Elevation and Plan of Overhead Wire.- 
House 



ri 



T/mmmjf; 



TjTTJTTTTTt^ 



t 



VTT77frmrmT77777777]7 



W7m77777777m777m77777/777P7, 





























To Ground ^x^'^ 






















'^^ 




Terminal ^""^v^^ 






















^^"^^ 


























/ 




<-io'> 

< 












- /06 


'.._ 






— > 







Plan of Ground Wires. 
Fig. 113. — Plan of overhead and ground wire system 

with a piece of heavy stranded copper wire. All joints 
were soldered before the wires were buried. The ground 
lead was a piece of Xo. 4 stranded copper wire leading 



206 



HIGH FREQUENCY APPARATUS 



down a side of the house from the transformer apparatus 
and making connection with the nearer bridging wire be- 
neath the ground. 




Soldering the buried wires 

To Right Me f hod of Overcoming 
the Weight of our Aerial Network 



.4--7" 



K- '55- -H 

Plan of Ground Wires. 




Fig. 114. — Plan of ground wires and method of putting in posts 



FURTHER NOTES OX PLANT CULTURE 



207 



The aerial network was formed by stretching four 
stranded copper wires between insulators secured to the 
supporting posts in the four corners of the electrified plot. 
Guy wires and turnbuckles stiffen the structure and en- 
abled us to make the network taut. Smaller copper wires 
were stretched between the stranded conductors, forming 
the closed loop as shown in the drawing. All joints in this 
network were carefully soldered with the aid of a blow 
torch. A rat-tail, composed of wires leading from each of 




Fig. 115. — ]\Iethod of holding overhead wires to posts 

the longitudinal stranas, leads directly to the switch out- 
side the house which formerly served the purpose of a 
lighting switch when the wireless outfit w^as in commis- 
sion. Indeed, the scheme of connection is exactly the same 
as that employed for wireless, the switch being so arranged 
that when current is not being sent through the network 
the switch connects the aerial network with the ground 
wires. 



208 



HIGH FREQUENCY APPARATUS 



1 



Construction Difficulties 

A shelf of rock runs beneath the entire plot under cul- 
tivation. The depth of the soil varies from less than a 
foot to over four feet at different points. While this forms 
an ideal condition from the standpoint of vegetable raising, 
in view of the fact that it maintains practically a constant 
state of moisture in the earth, the rock caused no little dif- 
ficulty when we undertook to erect the supporting poles for 
the aerial network. As the strain on the poles is consid- 
erable, we found it necessary thoroughly to guy the poles, 

Transformer Housq 









ijs 


— ; 

Check P/o^ ^ 


r 


























W\ 


(Not electrified) ^ 








\\ 






1^ 






\ 




^ 


5h 


• 1 




^ 55' --> 





Fig. 116. — Connections of ground wires 

and in this connection were forced to resort to various ex- 
pedients such as the use of convenient trees upon which to 
fasten the guy wires. Where this was found necessary, 
we protected the bark by placing strips of wood under the 
loop of wire where it passed around the tree. In other 
cases, we were forced to rely upon stakes driven into the 
ground. We are not certain that the latter will stand the 
strain, and we may find it necessary to use ''dead-men'' at 
the ends of the guy wires. Be it understood a ''dead-man" 
in this case is an anchor-like contrivance buried in the 
earth. 



FURTHER NOTES OX PLANT CULTURE 



209 



We used one 10-in. strain insulator of the high-tension 
variety at each pole. 

In erecting the network, the posts were placed about 
two feet in the ground. In this comparatively small plot 
only four posts were used. The guy wires were placed 
next without any attempt being made to tighten them. 
Finally the stranded wires forming the closed loop were 
stretched tightly between the insulators on the posts and 
the joints soldered to insure non-loosening and good con- 




Fig. 117. — Soldering ground wires with torch. 

I ductivity. The turnbuckles were next brought up to 
stretch the loop tightly. The longitudinal wires, five in 
number, were next stretched tightly between the two end 
( wires of the loop. These points were soldered. Then the 
, three transverse wires were stretched between the side 
j wires of the loop and the joints soldered. This gave us a 
' perfectly taut network of ample height to permit freedom 
I of movement underneath it in cultivating the garden. 



210 



HIGH FREQUENCY APPARATUS 



Vegetables Planted 

Radishes, lettuce, peas, carrots, beets, onions, potatoes, 
and celery were planted in the garden. 




I 
I 



Fig. 118. — Using small cultivator to prepare soil 

Apparatus Required 

Mr. Pickslay was the owner of a Clapp-Eastham Hy- 

tone transmitter of J^ k.w. capacity, and this transmitter 

was used to produce the necessary current. 



Projective 
Condenser 



g . 

"•- =^ Aerial 
Networ/c 



Line 




Fig. 119 

The secondary of the oscillation transformer was com- 
posed of 100 turns of No. 18 annunciator wire wound in a 
single layer upon a cardboard cylinder 5}^ in. in diameter 
which slips within the edgewise-wound copper strip form 



FURTHER NOTES ON PLANT CULTURE 211 

ing the secondary of the oscillation transformer used for 
wireless purposes. This coil gives less than a half- 
inch spark when operated without any capacity attached to 
its terminal ; however, when the aerial network is attached, 
the potential is so increased that a spark several inches 
long may be drawn from the coil. The diagram of connec- 
tions is given in Fig. 119. 



CHAPTER XIX. 

A FOREWORD ON THE CONSTRUCTION OF 
ELECTRICAL APPARATUS FOR THE STAGE 

In this chapter, the aim will be to present comprehen- 
sive directions covering the design and construction of 
the apparatus used in an elaborate electrical act suitable 
for the vaudeville stage. While many so-called electrical 
acts are already in the field, the effects produced are com- 
paratively insignificant when one stops to consider the pos- 
sibilities in this form of entertainment. No doubt most 
readers have seen the offerings referred to and the ''stunt" 
of taking several thousand volts of electricity through the 
human body is by no means a new one at the present day. 
However, it is thought that the quipment to be described 
will offer many opportunities for the enlargement of the 
previously attempted exhibitions of the wonders of elec- 
tricity with the result that the production, from a theatri- 
cal standpoint, will be sensational. 

In this apparatus, the high-frequency current plays a 
very important part ; indeed, many of the experiments are 
wholly dependent upon this form of current for their pre- 
sentation. Therefore, it is thought advisable briefly to re- 
iterate the nature of this current and its physiological ef- 
fects upon the human body. It was discovered many years 
ago that if an alternating current of electricity be caused 
to oscillate with sufficient frequently, that is, to change its 
direction of flow a sufficient number of times per second, its 
muscular contractive effects upon the body would be les- 

212 



ELECTRICAL STAGE APPARATUS 213 

sened to a considerable degree. The commercial alternat- 
ing lighting current which has a frequency of 60 or perhaps 
125 cycles per second, is fatal to a human being if applied 
in sufficient quantities. Available data discloses that volt- 
ages of from 200 to 500 are dangerous and in some cases 
fatal where the frequency is of the commercial order. If, 
however, the frequency is increased to 10,000 cycles and 
upward per second, it has been found that several thousand 
volts may be taken through the body with comparatively 
little discomfort. A further increase to 100,000 cycles and 
over renders the current practically painless. The possi- 
bility of using this peculiar form of current in the produc- 
tion of unusual effects will therefore be appreciated. 

Points to Consider. — Before starting work on any of 
the apparatus, the reader had best satisfy himself in his 
own mind just what feature of entertainment w^ork he de- 
sires to take up. This section deals with the construction 
of practically every useful form of high frequency appara- 
tus designed especially for theatrical demonstration. The 
assembly of the entire lot of apparatus as described would 
entail a considerable expenditure of time and money and 
there are cases where this outlay is scarcely justified. For 
instance, the platform lecturer would scarcely care to bur- 
I den himself with the costly and cumbersome equipment 
so essential to the performer on the stage. For the benefit 
i of readers to whom this elaborate equipment does not ap- 
I peal, a summary of the various types of outfits will be made 
. in order that the worker may make an intelligent selection 
J whether he be a modest '^suit-case'' lecturer or vaudeville 
; performer, a parlor entertainer, or a theatrical producer of 
ithe most extravagant type. 

The one big feature of any electrical offering is the 

high frequency work. This fact is admitted by dozens of 

jperformers and lecturers alike. The very idea of ''taking 



214 HIGH FREQUENCY APPARATUS 

thousands of volts'' of electricity through the body and still 
living to do it over again, is theatrical in the extreme, and 
it is no wonder that so many so-called electrical kings have 
separated a gullible public from their dollars for years on 
the sole claim that a supernatural or other unusual power 
made it possible for them to take current at this enormous 
voltage through their bodies. The high frequency coil 
may, therefore, be regarded as the one essential part of 
the outfit, and the other instruments in the light of ac- 
cessories. 

Weight and Cost of Apparatus. — The largest apparatus 
described in this section will deliver sparks several feet 
in length. That this is spectacular and impressive, no one 
will gainsay, but the outfit weighs hundreds of pounds and 
requires for its operation several kilowatts of electrical 
energy. The utter uselessness of such apparatus, in the 
case of the lecturer, is at once apparent. Far better is it 
for him to make or purchase a small coil capable of giving 
an eight or a ten inch spark and taking its current from the 
nearest lamp socket. Furthermore, the large apparatus re- 
quires for its operation an alternating current, and this is 
not always obtainable. The only practical alternative is a 
rotary converter or motor-generator set, which in this 
large size, is very heavy and costly. 

The small coil, on the other hand, may be built on 
the ''kicking coiF' principle, described in an earlier chapter, 
and in such event its operation is satisfactory on either di- 
rect or alternating current through the change of a simple 
connection. 

The question of the high frequency outfit therefore 
resolves itself into one of whether the performance is to 
be given in a chain of small lecture halls or good-sized 
theatres. In the former case the small portable outfit ^ 
is ample and certainly far more useful, while the latter use i 




ELECTRICAL STAGE APPARATUS 215 

would justify the best aggregation of paraphernalia the 
capital of the owner would command. The salaries of fea- 
ture vaudeville acts are, as a rule, commensurate with the 
pulling power and therefore the attractiveness of the act 
itself. Recognizing this, it is certainly wise to put forward 
every effort in an endeavor to make the true vaudeville act 
as big, as spectacular, and, to sum it up, as impressive as 
may be possible. The results justify the expenditure. 

In the construction of the apparatus the average reader 
is face to face with a problem. The manufacturer of stand- 
ard apparatus will not even quote on this special material ; 
the model shop wherein inventions are developed is too 
i thorough and expensive ; the average electrician knows 
I nothing whatsoever about the apparatus in question ; the 
I typical machinist is worse than useless where complete 
^ assembly is concerned, as he is either too ''rule of thumb" 
I or too literal. The reader will wonder what he is to do. 

The Home Workshop. — The answer is to build a home 
workshop. It is cheaper in the beginning and in the end, 
i and if the apparatus is worth having and building, it 
is deserving of a proper birthplace. The tools required 
may be purchased for perhaps a quarter of the sum de- 
manded by the combined carpenters, machinists, electri- 
cians and the rest of the vast army of mechanics, each one 
of whom does not know just what is desired, but is certain 
j that he is capable of building it just the same. 

The construction is best done in a spacious room 
wherein the apparatus can also be set up and tested, and 
the act rehearsed. This means, of course, the installation 
of electric service. The room should have plenty of open 
floor space rather than spacious work benches, although 
these are quite as essential within reason. The tool equip- 
1 ment may consist of a fairly complete set of wood-working 
tools and bench, an engine lathe of light construction but 



216 HIGH FREQUENCY APPARATUS 

of large capacity as regards swing, a small drill press and 
complete set of metal tools, such as pliers, hacksaw and 
files. With such an equipment the handy man — and it is 
assumed that the would-be entertainer is a handy man or 
he had better not start on the road with his outfit — may 
construct the entire set of apparatus with the assistance of 
a bright boy or even girl if she be mechanically inclined. 
And after the apparatus has been built by the man who 
intends to use it, who can gainsay the fact that he, better 
than anyone else, is prepared to take care of it and repair 
it if necessary? If some of the more intricate machine 
work, of which there is little, is beyond the capabilities of 
the amateur, then let him go to th^ regulation shop and 
have just that part finished up to drawings. 

Working Drawings. — The question of drawings brings 
us to a point of vital importance. Before a stroke of work 
is done on the apparatus, each and every part should be 
depicted in a large drawing and all dimensions checked to 
determine their -accuracy. The space available in this book 
has not rendered it possible to cover this detail with all 
thoroughness, but the individual worker should develop 
his design from the suggestions given, making his draw- 
ings complete in order that he may fully understand the 
construction of the various parts. 

In no sense is the work of building the apparatus diffi- 
cult and neither does it require the services of skilled labor. 
The ability to use tools in an intelligent manner and, what 
is far more important, a fairly intimate knowledge of the 
apparatus being built, may be said to constitute the quali- 
fications for success. In order that the latter qualification 
may be obtained, it is suggested that the prospective builder 
diligently consult every book pertaining to the subject that 
he can lay his hands on. These books may be numbered 
on the fingers of one hand, and when one has assimilated 



ELECTRICAL STAGE APPARATUS 217 

their entire contents, there is still a good deal to learn on 
the subject. But every iota of knowledge helps, particu- 
larly in the theoretical end, which does not necessarily 
mean the mathematical end. Probably the less mathema- 
tics the practical builder tampers with, the better he will be 
off, for the actual design of the apparatus has been spared 
him. What he needs is a good, sound knowledge of the 
characteristics of the high frequency current, and this may 
be quite readily obtained from a few good books. With 
knowledge and a fair equipment of tools, let him start in 
with what will probably prove to be the most interesting 
and fascinating w^ork he has ever attempted. 



CHAPTER XX. 
THE CONSTRUCTION OF LARGE APPARATUS. 

The construction of a high frequency transformer cap- 
able of throwing a five-foot spark will be considered first 
of all, for this piece of apparatus is probably the chef 
d'oeuvre of the assembly. 

The transformer consists essentially of a primary coil 
B, Fig. 120, of nine turns of heavy copper ribbon 2 inches 
wide and wound in the form of a spiral ; a secondary coil of 
600 turns of copper wire wound upon a wooden cylinder, S, 
Fig. 120; and a suitable means for holding the primary and 
secondary in their proper relation to each other. 

The secondary cylinder presents the greatest construc- 
tional problem for the amateur workman and it is suggeste 
that this be made at the mill unless the workman 
equipped with a large speed lathe. The cylinder is built 
up of segments of whitewood, tapered to fit around the 
periphery of three wooden discs, one at each end and one 
in the center. The entire cylinder must be assembled 
without the aid of nails or metal of any kind and the best 
course to follow is to glue the slats or segments in place 
and further to secure them with wooden pins covered with 
glue and driven into holes drilled into the wood. The 
cylinder is 50 inches long and 20 inches in diameter. After 
the assembly is completed, the surface should be turned 
off in the lathe and given two coats of a black vegetable 
dye. All paints containing lead and carbon must be 
shunned in the treatment of this apparatus or electrical 

218 



;s 






CONSTRUCTION LARGE APPARATUS 219 

'"leaks" will be developed. There are several good black 
dyes on the market soluble in water or alcohol and any one 
of these may be used with impunity. After the surface of 
the cylinder is blackened and thoroughly dried, it may be 
given a coat of shallac, when it is ready for winding. 

The winding is best done in a screw-cutting lathe as 

the turns are to be evenly spaced 12 to the inch. If the 

lathe is not available, an improvised winding machine may 

be constructed with, the aid of two bearings to support 

the cylinder and a length of rod threaded 12 to the inch 

arranged to turn with the cylinder and to carry a guide 

for the wire as it is wound. The winding is of No. 22 

D.C.C. magnet wire and the first turn is started 1 inch from 

one end of the cylinder. From this point it continues to 

I within a like distance of the opposite end. A band of 

i J4"ii^ch copper ribbon is then placed around the remaining 

space at either end and the starting and finishing ends of 

I the winding are soldered to the bands. The latter should 

( not completely encircle the cylinder but a gap of % inch 

should be left where the ends meet. The winding is to be 

given four coats of shellac, each coat being permitted to 

dry thoroughly before applying the next. 

A brass bushing, having in it a hole tapped ^^-18, is to 
be firmly secured in each head of the cylinder and connec- 
tion made from the copper bands to the bushings. 
I Wooden discs, 21 inches in diameter, are to be fitted 

I to the ends of the secondary cylinder in order to give it a 
finished appearance. Holes are bored through the centers 
I of the discs, of course, to permit access to the bushings 
1 within. 

I The secondary cylinder is surmounted by a discharger 

composed of a brass ball mounted on the end of a rod 

, which makes contact with the brass bushing in the top of 

j the cylinder. A wooden cone is turned up in imitation of a 



220 



HIGH FREQUENCY APPARATUS 




Fig. 120. — The oscillation transformer complete 



L 



CONSTRUCTION LARGE APPARATUS 221 



high tension insulator and the rod carrying the ball runs 
through the center of this cone. 

The construction of the primary coil and base will be 
understood on reference to Fig. 121, which gives a plain 
view looking down on the primary from the top and also a 
side elevation of the lower portion of the complete trans- 
former in cross section. It will be noted that the primary 
is composed of nine turns of heavy copper ribbon two 

! inches wide and wound in the form of a true spiral. The 
ribbon is wound into its finished form with a double thick- 
ness of -^Q inch rubber belting between turns. It is taped 
at three or four places to hold it in place temporarily while 

! the supports are being constructed. 

The object of elevating the primary coil is to provide 

, means of access to the under side in order that connection 

' may be made with any desired turn. The coil is gripped 
between pieces of fibre bar A which are held in place by 
fibre bolts B and the whole is supported on the elevating 
posts C of fibre. 

The base is of wood, and it should be mounted upon 
four glass or porcelain insulators. The finish of the base 
is preferably of the same color as that used on the sec- 
ondary cylinder; the black vegetable dye provides a finish 
that is rich and pleasing in appearance and at same time 
rather unusual. If the copper primary ribbon is highly 

; polished and lacquered, a pleasing contrast will result. 

I A square wooden box is mounted upon the base and 

in its top is a short bolt threaded to enter the hole in the 

j brass bushing in the lower end of the secondary cylin- 

\ der. A strip of copper ribbon makes connection between 

! the bolt and inside turn of the primary spiral. 

Connection between the primary and the balance of the 

, circuit is established by means of special flexible cables 
which are made by binding 100 strands of No. 32 S.C.C. 



222 



HIGH FREQUENCY APPARATUS 




Fig. 121. — Section through base of oscillation transformer and plan view of primary 



CONSTRUCTION LARGE APPARATUS 223 

magnet wire with cotton tape. Each of the two cables 
should be about 5 feet long and tipped on each end w^ith 
a special lug or connector. The construction of the con- 
nector or clip which makes contact with the primary rib- 
bon is clearly shown in Fig. 122. The clip is made by cut- 
ting a slit in the end of a piece of hard brass rod ^ inch in 
diameter by means of a thin hacksaw. The blades are ren- 
dered more springy by cutting away a portion of the metal 
from the back of each, and a hole is drilled into the shank of 
the clip to admit the wire of the cable. Each strand of 




Fig. 122. — Clip which makes connection with primary turns 

the latter is carefully cleaned of its insulation for a dis- 
tance of Yz inch and the bare ends of the wire are then 
twisted together after having been well coated with a good 
soldering paste. The clip is held in a pair of pliers and 
carefully heated over a Bunsen flame until the solder melts 
within the hole, after which the cable end is carefully in- 
serted and sweated in the clip. The wire, where it enters 
the clip, is tightly bound with thread until it is equal in 
diameter to the shank of the clip. A piece of fibre tubing, 
making a tight fit over the shank, is then forced on and 
extended over the binding of the wire. This serves as a 



224 



HIGH FREQUENCY APPARATUS 



protection for the cable where it is joined to the connector 
and provides a suitable handle as well. 

In Fig. 123 is given a diagram of the connections of the 
complete transformer and the reader will note that th^ 
connection to the primary spiral is variable over quite 
a wide range. In operating the transformer, it is necessary 
to make various trials in order that the correct number of 




Fig. 123. — Diagram of connection for the oscillation transformer 

turns to produce resonance may be determined. The point 
at which the secondary coil makes contact with the inside 
turn of the primary should always be grounded on the 
nearest water pipe. This will not only safeguard the per-i 
former from the liability of dangerous shock, but it will 
prevent high tension surges of current from striking back 
through the remainder of the apparatus with disastrous 
results. 



COXSTRUCTIOX LARGE APPARATUS 



225 



The Transformer. — The transformer required for the 
operation of the coil described may be rated at approxi- 
mately 4 k.w. It may appear to some engineers that the 
instrument is somewhat overrated, but in view of the fact 




J Fig. 124. — Details of the cure with dimensions 

;that it is in use for periods of less than 20 minutes at a 
'time it is believed that no difficulty will be experienced. 

The core is built up of sheets of silicon steel .017 inch 
•thickness and cut to the sizes show^n in Fig. 124. Refer- 
jence to this drawing w^ill disclose the fact that 448 pieces of 



226 



HIGH FREQUENCY APPARATUS 



each of the two sizes will be required. It is suggested 
that this steel be purchased from some transformer manu- 
facturer already cut to size, as it is practically impossible 
to buy silicon steel in such a small quantity in the open 
market. Assuming that the steel has been obtained, the 
legs A and E of the core may be assembled by placing the 
pieces alternately first to the right and then to the left, 
showing a 3-inch overlap as indicated in Fig. 125. Each pile 
will have assumed a thickness of approximately 4 inches at 
this time and the pack should be tightly compressed in a 




Fig. 125. — Short leg of core on which winding is placed 

vise and bound with friction tape. The pieces forming the 
leg B may then be inserted one at a time to form the con- 
necting yoke. This is rather a tedious process, but it offers 
the only practicable method of making a joint that is both 
mechanically strong and good from a magnetic standpoint. 
The core may then be set aside to await the primary and 
secondary windings before having its magnetic circuit com- 
pleted with the remaining sheet iron strips D, 

For winding the secondary, a form of square cross sec- 
tion similar to that shown in Fig. 126 should be employed. 
This form may be of wood and solid in construction. The 



CONSTRUCTION LARGE APPARATUS 



227 



corners should be slightly rounded. The dimensions are 
given in the drawing. After the form has been mounted 
in the lathe between a spur-chuck and a center, it should 
be covered with a winding of a single layer of cord. Over 
the cord is placed a -^^ inch thickness of oiled paper, then 
a layer of ^g inch flexible mica and finally 4 or 5 additional 
thicknesses of paper. Each layer of this insulation should 
be tightly secured with thick shellac in order to make a 
solid core or base upon which to place the secondary wind- 
ing. The latter is done in two sections, wound in opposite 
directions and having their inside ends joined together. 




Fig. 126. — Details of secondary winding showing wooden block or form upon 
which the wire is wound 

■^This end is attained by first winding one section and then 
'.reversing the secondary core upon the form and starting 
'the remaining half of the winding by joining the wire from 
the spool to the starting end of the first section. 

It will be noted that the two sections of the winding 
are divided by an insulating shield of mica which is cut 
to fit over the core and placed in position when the first 
"section has been completed. The starting and finishing 
lends of the winding are soldered to pieces of thin copper 
'ribbon about % inch wide. After both sections have been 
^completed the finishing layer in each should be covered 
(with oiled paper to a thickness of -^q inch. 



228 HIGH FREQUENCY APPARATUS 

The secondary winding consists of 3,525 turns of No. 
25 enameled wire wound 75 turns per layer and 41 layers 
deep in each half of the secondary winding. Each layer 
of wire is separated from its neighbor by two layers of 
oiled paper which should be purchased in the form of a 
roll of paper tape two inches in width. As No. 25 wire 
winds 51 turns per inch it is obvious that there will be a 
margin of about ^4 ii^ch along either side of the layer of 
wire. i 

The finished secondary is given a coat of armalac and 
the edges of the paper layers are liberally plastered with 
the compound in order that moisture may be prevented 
from entering. After the composition has dried, the sec- 
ondary may be placed in position on one of the shorter legs 
of the core. 

The primary is composed of 100 turns in all of double 
cotton covered wire. The first 70 turns to be wound should 
be of two No. 8 wires wound in parallel and the remaining 
30 turns should be of a single No. 7 wire. Taps of heavy 
copper ribbon are to be brought out at 70, 80, and 90 turns 
in order that four variations of power may be available. 
The primary may be wound on the same form as the sec- 
ondary and the insulating core on which it is wound should 
be built up similar to that on which the secondary was 
wound. The cord is wound upon the form in order that 
the coils may be removed without difficulty merely by 
withdrawing the cord. Short lengths of No. 8 stranded 
conductor are soldered to the primary taps to establish con- 
nection with a regulating switch. The primary may then 
be placed on the remaining leg of the core and the end 
pieces inter-leaved to complete the magnetic circuit. 

The entire transformer may then be mounted in a suit- 
able case of wood as shown in Fig. 127. Wooden blocks 
placed above and below the core serve to hold the trans- 



CONSTRUCTION LARGE APPARATUS 



229 



former securely in position and the case is supplied with 

handles as shown in the drawing to facilitate carrying. 

The primary and secondary terminals should be mounted 

inside the cover in order that the working parts of the in- 
' strument may be entirely enclosed and thus protected from 

injury in shipment. If the case is substantially made it 
; will serve as a shipping crate of convenient and effective 

design. 

The secondary wires are brought to suitable terminals 

mounted on pillars of fibre inside the box while the pri- 
^ mary terminals are brought to the contacts of a regulating 

switch likewise mounted on the wall of the case. The 




Fig. 127. — Case or container for the transformer 

winding of the transformer is so designed that a consump- 
tion of current varying from 2 to 4 k.w. may be obtained. 
The Spark Gap. — The apparatus previously described 
is designed for use with a rotary spark gap. Reference to 
Fig. 128 will disclose the fact that the spark gap is of sim- 
ple construction and that it consists essentially of a disc of 
^-inch aluminum, carrying 12 discharge points or studs 
of nickel steel, mounted upon the shaft of a small alternat- 
ing current motor and surrounded by a housing of wood 
which serves the double purpose of a muffler to deaden the 



230 



HIGH FREQUENCY APPARATUS 



noise of the spark discharge and a support to carry the 
stationary electrodes E in Fig. 128. The drawing repre- 
sents a side elevation of the complete gap shown partly in 
cross section in order that the relative positions of motor, 
rotary disc and stationary electrodes may be shown. Fig. 
10 shows an end elevation of the gap housing and it also 
serves to indicate the position of the stationary electrodes. 
Attention should first be directed to the rotor oi 
the gap. This should be laid out on a piece of ^-inch 
sheet aluminum rather more than 10 inches square 
After finding the center, a circle with a diameter of 10 
inches is inscribed upon the aluminum and then a 9-inch 




Figs. 128 to 131 inclusive. — The rotary spark gap complete and in detail 

diameter circle is laid out and finally one of 3-inch diame- 
ter. The sheet of aluminum is then mounted upon a 
wooden faceplate in the lathe and a cut taken quite through 
the metal on the line of the smallest circle, thus leaving 
an opening 3 inches in diameter when the disc of metal is 
removed. A similar cut is taken on the largest circle re- 
sulting in the rotor disc which is now ready to be mounted 
upon the insulating hub of fibre, indicated at C, in Fig. 130, 
which gives an elevation and section of the rotor disc 
complete. 

The insulating hub is turned up from a piece ^-inch 
sheet fibre to the dimension given in the enlarged drawing, 



CONSTRUCTION LARGE APPARATUS 231 

Fig. 131. The reader will note that the fibre hub is 
mounted upon a boss of brass which is threaded into the 
fibre and riveted over on the end to prevent its working" 
loose. The brass piece is drilled with a hole of a diameter 
to take the motor shaft and a set screw provides a means 
for securing the boss on the shaft. The final cut which 
brings the fibre hub to the diameter of the hole in the alum- 
inum disc should be made after the hub has been cut 
roughly to size and mounted upon the brass boss which is 
in turn mounted upon an arbor in the lathe. This will in- 
sure absolute truth in running. 

The aluminum disc should next be divided with 12 
radial lines running from the center and crossing the 9-inch 
circle at 12 equi-distant points. At each point a clearance 
hole for a No. 10-24 machine screw is drilled. Twelve cyl- 
inders each j^4-ii^ch long should be cut from a piece of 
nickel-steel rod ^-inch in diameter and each cylinder 
drilled and tapped in one end for a No. 10-24 screw. The 
cylinders ma}^ then be secured in position on the aluminum 
rotor and the disc mounted upon its hub of fibre. It is se- 
cured thereon with 6 rivets which may be brass escutcheon 
pins inserted in snugly fitting holes drilled through alumi- 
num and fibre. The heading over should be done very 
carefully and on the aluminum side. The rotor, which is 
now finished, may then be mounted upon the arbor in the 
lathe in order to test for accuracy in running and, if the 
final cut on the fibre hub has been carefully taken and all 
burrs removed from the edge of the openings, the disx: can- 
not run other than true. 

The reader's attention is next called to the housing 
which consists essentially of a box of suitable size built 
up from J^-inch whitewood and lined throughout with sheet 
asbestos. A hole is drilled in the rear of the box to ad- 
mit the boss of the rotor. The box is assembled with 



232 HIGH FREQUENCY APPARATUS 



^ 



screws throughout and the top piece, D, Fig. 128, is made 
removable in order to afford access to the interior of the 
case. The front of the box carries the stationary elec- 
trodes of the gap and the construction of these demands 
our attention next. 

The stationary electrodes consist of a pair of the ^- 
inch nickel steel cylinders mounted upon threaded i%-inch 
brass rods supported in brass bushings which are threaded 
into the wooden front of the case. A 3-inch disc of fibre 
on the end of each of the threaded rods provides an adjust- 
ing handle by means of which the clearance between the 
studs on the rotor and the stationary electrodes can be 
closely regulated. A strip of heavy copper ribbon estab- 
lishes connection between each stationary electrode and a 
binding post placed a few inches beneath it. 

The gap may now be assembled according to Fig. 128 
which shows the relative positions of the various parts so 
clearly that further description is unnecessary. The motor 
may be of the ordinary fan motor type of ^^ H.P. or even 
less and its speed should be about 1800 revolutions per 
minute. The method of mounting the motor is, of course, 
dependent upon the nature of the base or bed plate. The 
builder's ingenuity will doubtless suggest the best form of 
mounting to meet his individual requirements. 

Care should be taken to see that there is practically no 
end play in the motor, for if such were the case, the clear- 
ance between the discharge points could not be maintained 
at a uniform value. 

The Oscillation Condenser. — Before proceeding with 
the description of the condenser, it may be well to state 
that this particular feature of the outfit presents many diffi- 
culties in its design in view of the fact that the condenser 
is to be subjected to much rough handling and moving 
about. The data offered herewith is for a condenser hav- 



CONSTRUCTION LARGE APPARATUS 



233 



ing glass plates for its dielectric, but the author would sug- 
gest that this material, while highly satisfactory for use in 
a condenser to be used in but one place, is obviously sub- 
ject to breakage and is at a further disadvantage from point 
of weight. Its use is suggested in this work merely be- 
cause the stock is readily obtained and this at a low figure. 
Sheet mica, while several times as costly, is far superior in 
every w^ay and its use is strongly recommended to those 



L, JL ^ 1 JL X J-, rJLn rU 



CONNECT SIX IN 
MULTIPLE ■— TWO 
\N 5EE.1E.5 



Fig. 132. — Showing how condenser is connected six units in multiple and two 

in series 



( who feel that the extra expense is justified by the advan- 
; tages gained. 

For the condenser proper, 120 sheets of 8 by 10 inch 
I photographic glass will be required. This glass, in the 
! form of discarded negatives, ma}^ be obtained from almost 
i any photographer for a small sum. In addition to the 
j plates above-mentioned, the builder will require some 24 
plates additional to serve as cover glasses for each con- 



234 HIGH FREQUENCY APPARATUS 

denser unit. A few extra plates to replace possible broken 
or defective ones will not be amiss. 

The first operation will be to clean the emulsion from 
the glasses and this is readily done by soaking the plates 
in hot water. It is not essential that the plates be made 
perfectly clean of the emulsion if the plates have all been 
developed and the silver dissolved, but it is desirable to 
get the surface and particularly the edges for a space of an 
inch or more as clean as possible. The plates, when 
cleaned and dried, are to be placed in a warm oven prior to 
having the metallic coating of tinfoil placed on each side. 
This coating is of the heavy foil used by florists and may 
be obtained in strips 48 inches long and 6 inches wide at 
almost any florist's shop. It comes in packages of one 
pound and averages some five strips to the package. The 
foil should be straightened out and cut off into rectangles 6 
■ by 8 inches in size in order that when secured to the glass 
it will leave a margin of an inch all around. (See Fig. 133.) 

The condenser is made up into units of ten plates eaclm 
and each plate is to be coated on both sides with the tin* 
foil. In all there will be 12 units connected up as shown in 
Fig. 132, that is, two sets of six units each connected series- 
multiple. 

To coat the plates the builder should provide a lump 
of beeswax and a ''pounce" made by enclosing a wad oil 
cotton within a soft cloth. A warm plate is taken from the 
oven and laid upon a cloth-covered table top. The lump 
of beeswax is rubbed lightly across its surface to provide 
a thin and even coating. A sheet of tinfoil is immediateljf I 
placed in the center of the glass and rubbed into close con- 
tact with the pounce, starting at the center and, with a 
circular motion, working out toward the edges. This will 
result in a perfect union of glass and foil at all points. The 
plate is immediately reversed and the other side coated in 



CONSTRUCTION LARGE APPARATUS 



235 



like manner before the plate gets too cold to melt the 
wax. The remainder of the plates are to be treated in a 
similar manner when they are ready for the connecting 
lugs, after having had their edges dipped in melted wax 
far enough to cover the edges of the foil for a space of an 
inch or so to prevent brush leakage. 

The lugs are of thin copper ribbon, tinned at one end 
and affixed electrically to the tinfoil at alternate ends on 
both sheets of foil with a deft application of the soldering 
copper. A little practice on a scrap plate will soon enable 
the worker to master the operation of soldering the copper 
to the foil without melting the latter. The drawings in 
Fig. 133 illustrate the location of the connecting lugs and 




I Fig. 133. — Single plate of the condenser coated on both sides with tin foil 

I also the way in which ten plates are piled one on top of the 
] other to form a complete unit. This assembling having 

been done with the entire lot -of plates, the projecting lugs 
i may be clamped with the pliers and soldered to short 
' lengths of copper ribbon ready for connection with the bus- 
' bars of the condenser. The plates of each unit should be 

bound with tape to afiford mechanical strength and ease of 
1 handling. A plain piece of glass is placed on either side of 
I each unit under the binding tape. 
! The twelve units are to be assembled in a strong 

wooden case and each unit should be separated from its 

neighbor by strips of wood covered with felt. Connections 



236 HIGH FREQUENCY APPARATUS 

are made as shown in Fig. 132, to bus-bars consisting of 
several strips of copper ribbon fastened together. The 
connections with the outside of the case are by means of 
heavy flexible cables made by binding a number of strands 
of fine insulated copper wire under one cover. 

Setting Up and Operating. — The connections of the ap- 
paratus are simple as the accompanying drawing shows, 
and it is only in some few particulars that the author need 
supplement with further explanation. (See Fig. 134.) 

A switchboard is highly desirable but not at all essen- 
tial to the successful operation of the apparatus. One may 
be made quite simply and without the expenditure of much 
time or money. A pilot lamp, to enable the operator to 
see the control switches in the dark; a 50 ampere doublel 
pole, single throw knife switch to control the transformer 
circuit ; and a small snap or knife switch for the spark gap 
motor circuit, will complete the equipment of such a simple 
board. This adjunct to the outfit may be made quite elab- 
orate, if desired, just for the theatrical effect it may have 
if placed upon the stage. In this event, the board, which, 
may be of wood treated with a fireproofing compound 
should be finished eventually in a dead black to simulate 
slate. The switch equipment may be supplemented with 
fuses, imitation bus-bars and additional lights. An am- 
meter and a voltmeter will not only add to the appearance, 
but will also be of practical service in the operation of the 
apparatus. 

The transformer requires a current of from 40 to 50 
amperes at full load and the leads from the stage pocket 
must necessarily be of heavy cable. The stage cable used 
in connection with motion picture arcs is admirably adapted 
to this purpose and the outfit should include from 50 to 
100 feet of cable. 

Connection between the transformer secondary and the 



CONSTRUCTION LARGE APPARATUS 



237 



rotary spark gap electrodes may be made with the high 
tension cable used in the ignition circuit of automobiles. 
This cable is to be fitted with substantial lugs as in use it 
will have to be connected and disconnected a great many 
times. 

The oscillation circuit comprising spark gap, condenser 
and primary of oscillation or high frequency transformer 
should be connected with the cable. 




Conejznser 



\\ 



6dp 



1 



— j— O t^inz 

I — ^ii- 



X 



O Linz 



Trdnsfbrmcr 



■^^^ (/round 



Fig. 134. — Diagram of connection for the apparatus 

Prevention of Kick Back. — The ground connection 
'Shown in the diagram is of the utmost im.portarice as with- 
|out it high voltage surge back through the transformer 
j wires will be almost sure to puncture the insulation of the 
(transformer. To further protect the latter and to safe- 
! guard the house wiring, a protective condenser should be 
j connected across the transformer primary at the point 
' where the line wires are connected. This condenser is 



238 HIGH FREQUENCY APPARATUS 

made by joining two 2-mfd. telephone condensers in series 
across the line and grounding the neutral point or wire that 
connects the two. 

For the sake of simplicity, the spark gap is shown as a 
stationary one rather than a rotary. The connections are, 
of course, the same for the two. 

When all has been connected up, the spark gap elec- 
trodes may be adjusted to the point where they just miss 
the rotating member and the gap motor started. For this 
first test, the primary clip of the oscillation transformer 
may be placed on the center turn to permit of variation in 
either direction as required to establish resonance. The 
main switch may next be closed and the ball discharger at 
the top of the oscillation transformer should send forth 
long streamers of fire with a terrific cackling noise. An 
adjustment of the clip on the primary from one turn to an- 
other, and a variation in the length of the spark gap, will 
soon enable the operator to obtain resonance. This point 
is indicated by the longest streamers. At its maximum ef- 
ficiency, the coil will send forth a spark that will dart a 
distance of more than five feet to a wire attached to the 
ground and brought near the discharge terminal. A 
strange feature of this experiment is the fact that the sec 
ondary cylinder is but 50 inches high and, rather than dar 
downwards, striking the primary of the coil, the spark will 
break down a far greater distance in a horizontal plane and 
still farther if the ground connection is placed overhead.^ 
This is a peculiarity of high frequency discharges. 



1 



CHAPTER XXI. 

LARGE TESLA AND OUDIN COILS FOR THE 

STAGE. 

In the present chapter, the specifications for two of 
the most popular types of high frequency transformers are 
given. The coils are complete in themselves and for their 
operation, the exciting apparatus described in the preceding 
chapter, or else the quenched gap apparatus covered in the 
former chapters, may be used. The proportions of these 
coils are excellent for transformers of larger or smaller size. 
The Tesla transformer illustrated in Fig. 135 is capable 
of throwing a 50-inch spark between terminals if made in 
the size shown in the detailed drawings, Fig. 136. This 
spark can be produced through the use of a two kilowatt 
transformer in the exciting circuit if the apparatus is tuned 
properly. The resonator shown in Fig. 137 is designed for 
the production of a comparatively short, but very heavy 
spark and it is capable of remarkable performances in the 
hands of an ingenious manipulator. The various experi- 
ments such as lighting lamps with current taken through 
the body and igniting cotton or paper with sparks taken 
from the fingertip are well within its scope and this on a 
big scale. The coil is also excellent for the generation of 

\ a very high frequency current at high voltage for the pro- 
duction of a bluish halo or glow which seems to come from 

I the extremities of the body when the performer operates in 
the dark. 

239 



240 



HIGH FREQUENCY APPARATUS 




LARGE TESLA AND OUDIX COILS 241 

Rather than attempt a minute description of -each op- 
eration in the construction of these coils, the author will 
endeavor to cover the constructional features in each case, 
believing that the reader is sufficiently well-versed in me- 
chanics to be able to read the drawings without difficulty. 
The construction is practically identical in the two designs 
and a description of one will suffice for the other. 

The most difficult part of the work is the building of 
the secondary drum indicated by 1 in the drawings. This 
is a wooden cylinder with wooden heads. The difficulty 
is found in the fact that the builder must not use metallic 
nails in the assembly. This is not insurmountable, how- 
ever, for the shoemaker uses a substitute that fills the bill 
I very nicely. His sharp wooden pegs may be driven like 

• nails if the precaution is taken to start the hole with an awl 
or drill. If the builder has no lathe, he may order the 

I wooden disc, which constitute the heads and intermediate 
I forms for the cylinder, turned to size, from the mill. The 

• wall of the cylinder is composed of wooden slats placed 
closely and glued and pegged to the discs. The construc- 
tion will be materially assisted if holes are bored in the 
discs prior to assembly and a long curtain pole passed 
through to line them up. The pole is removed before the 
last few slats are placed in order that the brass bushings 
shown in the cylinder heads may be inserted and secured. 
After this, the final slats are placed in position, glued and 
pegged. 

The cylinder may next be mounted upon a pair of 
{horses and arranged to revolve through the agency of a 
I short length of iron rod screwed into each bushing. The 
I rod should be flanged in back of the threaded portion to 
! prevent the strain on the bushing that would otherwise 
' be present. With the cylinder between horses and a staple 
(driven over each spindle, the builder may proceed to finish 



242 



HIGH FREQUENCY APPARATUS 




U>^ 



LARGE TESLA AXD OLDi:: COILS 243 

off the surface. A plane run along the slats will take off 
the projecting corners and a final rubbing v/ith coarse sand- 
paper will bring the surface to a fairly smooth condition. 

The winding surface is prepared by covering the cyl- 
inder with several layers of heavy wrapping paper, each 
layer being thoroughly soaked with shellac before the next 
is applied. The easiest and best way to do this is to pur- 
chase a roll of paper and place it in hangers beside the 
cylinder. The Tesla secondary may be wound in two sec- 
tions with a space between at the centre of the coil. This 
space will provide for the legs that support the primary 
helix as shown in the drawings. The wrapping paper need 
therefore be only half the length of the cylinder in width 
ki order to fully serve the purpose. 

When the cylinder is covered and the paper and shellac 
have dried quite hard, the winding may be done. The 
exact size of the wire on the Tesla secondary is of small 
importance. The only requisite is that the number of turns 
;be kept between 600 and 800. There should be an appre- 
ciable space between each turn and its neighbor, however; 
and this may govern the gauge of the wire employed. 
It is difficult to secure any w^ire larger than No. 22 in a 
length sufficient to wind the cylinder in one piece and a 
splice is not to be desired. If, therefore, Xo. 22 B. & S. 
gauge, double cotton covered magnet wire is available, it 
may be wound 12 turns to the inch, making in the neigh- 
jborhood of 300 turns in each half of the winding. The 
two halves of the winding must be in the same direction ; 
that is to say, the one half is a continuation of the other. 
[This is easily assured by starting at the left end of the 
cylinder, for instance, and winding until within 1^ inches 
of the centre. Here the wire is secured with a w^ooden 
peg and a jump taken over 1^ inches to the other side of 
the centre of the cylinder. Another peg secures the start- 



244 HIGH FREQUENCY APPARATUS 

ing turn and the second half of the winding is completed, 
turning the cylinder in the same direction. In order tell 
maintain the space between turns a loop or cord is passed 
over the cylinder and a weight hung from its lower point. 
The turn of cord, which should be heavy and approximately 
-^Q inch thick, will guide each succeeding turn, spacing thenlj 
with fair accuracy. An experimenter who has built a sell 
of apparatus recently from the author's directions, advises ' 
that he was able to straighten up the entire winding by 
running a metal comb along the wire as an assistant turned 
the cylinder. The winding, when finished, is given half a 
dozen coats of shellac, each coat being dried thoroughly 
before the next is applied. 

The construction of the helix forming the primary will 
readily be understood from the drawings. The conductor 
is a length of ^-inch copper tubing, rubbed bright, and 
coiled into a helix of 27}^ inches in diameter for the Tesla 
coil and 26 inches in diameter for the resonator. A ma* 
terial superior to the tubing is the edgewise-wound copper 
strip that is now used in nearly all high grade wireless 
transmitters. This strip can be purchased in a spiral from 
any large wire manufacturer, but to bend it edgewise with- 
out buckling is a mechanical problem worthy of an engi- 
neer. It can be done by rigging up a drum of metal ar- 
ranged with clamps to hold the strip flat as it comes fronj 
the reel, but the task is scarcely one within the province 
of the amateur. 

The Tesla coil is mounted upon a base equipped with 
casters in order that it may be moved quickly and easily. 
The secondary is supported by four rods of wood which 
are mounted in wooden bases in imitation of high tension 
insulators. The secondary is removable from the support- 
ing rods merely by lifting it ofif, the rods terminating in 
plugs which fit sockets in the heads of the cylinder. The 

f 



LARGE TESLA AND OUDIX COILS 



245 




1 req'd j ccmp/ete re(^<:f. 



Fig. 137. — The Oudiii resonator complete and in detail 



1 

I 






246 HIGH FREQUENCY APPARATUS 

rods themselves are removable from the base by liftin 
them from sockets therein. The primary helix is supporter 
on the secondary cylinder by the three legs as shown in 
the drawings. The helix is so springy that there is n 
difficulty in springing the third leg into position after th 
helix has been placed over the cylinder. 

The object of having all of the parts removable is o 
course to permit packing to be done effectively and withou 
the enormous cases that would be necessary if the coii 
were in one piece. The resonator is made separable in 
the same manner. 

The ends of the Tesla winding are connected to th 
discharge rods through the rods and balls shown in the 
sectional drawing. The primary is entirely independent and 
its only connection w4th the secondary is an inductive one. 
With the resonator, however, the case is different. The 
lowest turn is connected to the bottom turn in the primarj 
helix and this in turn to a common ground terminal. Th( 
discharge rod 4 is also connected with this ground win 
beneath the base. 

Regarding the resonator, little further need be saic 
save for a few words about the winding. This is in one 
continuous layer of about 350 turns. As the voltage ii 
lower, this winding may be of No. 18 annunciator wire 
wound close and most carefully coated with shellac in six 
applications. The practice of winding the turns close is to 
to be avoided if possible for there is extreme likelihood of 
the current leaping across through the insulation. A sep- 
aration of a single turn of thin cord will help materially. 

In closing it may be well to state that the suggestions 
given in this chapter are intended for the amateur worker 
who is not equipped with a lathe sufficiently large to takef 
the cylinders. If the individual is so fortunate as to have 
access to such a large lathe, he may disregard most of the 
instructions and proceed in the regular manner. 



CHAPTER XXII. 

THE CONSTRUCTION OF A WELDING 
TRANSFORMER. 

While this piece of apparatus can scarcely be placed 
in the category of high frequency apparatus, since the cur- 
rent employed is the ordinary 25, 60, or 125 cycle lighting 
current, still the welding transformer forms a valuable ad- 
dition to the high potential apparatus used in an electrical 
offering on the stage. The feat of grasping a piece of iron 

( wire, as thick as a pencil, between two pairs of tongs held 
in the hands and causing the wire to become red and even 

■ white hot while held in that position, is a stunt which 
seldom fails to call forth the applause of an audience. 
When the experiment is conducted with the proper scenic 
atmosphere, the effect is materially. enhanced. 

In this chapter the reader will find the details of the 
construction of a low-voltage transformer admirably 
adapted to this purpose. The transformer can be built by 
the average handyman who has a smattering of electrical 
knowledge and Avho knows the value of careful work as 
regards insulation. Later in the chapter, the design of a 
suitable stage setting and accessories will be described. 
While this experiment may readily be made one of a num- 

,ber grouped up into a single oft'ering, still it is quite com- 
plete in itself and with embellishments, it may form the 
basis for an act of a few minutes' duration. 

In order to make the description clearer, the various 
parts of the transformer will be described separately, each 

247 



i 



248 HIGH FREQUENCY APPARATUS 

under Its proper heading. The transformer is designe 
for operation on a 110- volt, 60-cycle alternating curren 
circuit and when the load is applied, the current in the 
primary is approximately 26 amperes. The secondary cur- 
rent at 11 volts is in the neighborhood of 250 amperes and 
this is sufficiently large to make quite a display. 

The Core. — The core of the transformer is of lam- 
inated iron or preferably silicon steel .017 inch thick and 
cut into pieces as indicated in Fig. 138. From the diagram 
the reader will note that two sizes are required, i. e,y 3 by 6 
inches and 3 by 8 inches, respectively, and 340 pieces of 
each size will be needed. The steel for the core may be 
obtained cut to size and ready to assemble from certain 
transformer manufacturers who buy the material in large 
quantities and cut it with a gate shear. 

Fig. 140 shows how the 3 by 8 inch pieces are as- 
sembled with the ends projecting alternately three inches 
first on one and then on the other side. The strips are di 
vided into two piles of 170 pieces each and each pile is then! 
built up as shown in Fig. 140 to make two cores, each three 
inches thick. A generous wrapping of tape and three 
layers of press board make the cores ready for the 
windings. 

Primary and Secondary Winding. — The secondary i^ 
wound over the primary on each leg of the transformer. 
For this reason the primary winding will be considered 
first. As mentioned before, the winding described is for* 
use on a 110- volt circuit; if the builder desires to wind foq 
a 220-volt circuit, he should substitute twice as many turns 
of a wire three sizes smaller in the primary only. The 
windings here mentioned are figured at but 500 circular 
mils per ampere, but in view of the fact that the trans- 
former is used for only a few minutes at a time, the heat- 
ing will not be excessive. 



j 



CONSTRUCTIOx\ OF WELDING TRANSFORMER 249 

The primary consists of 120 turns in all and so ar- 
ranged that 90 turns may be used if desired. The wind- 
ing is of No. 9 D.C.C. magnet wire in four layers of 30 
turns per layer. Two layers are wound on each leg. With 
reference to Fig. 142, the winding is started by soldering 
the end of the wire from the spool to the end of a piece of 
stout copper ribbon which is then insulated with a layer of 
paper and the winding continued over it for one layer. This 



4 


B 


4 

i 


ri<).t 


B A 




1_ 


.^•_IrJ 





J Core f'ronj y^e' 34o pcj 
Core or^Uicon 6tQe/ .on' thfch. 





Core leg Toped reo<f(/ 

for )rind/ng. 

tTojpoo/ 



r~rf 



To^poof 



^hO¥ving method of Ouf/d/ng 
up core /rorxx 



^ r'9-^ 




Ribbon to which f/'niih in { 
end i\5 soldered 



fif? 



When 45 fh. turn /3 trouna 
colder to r/bbon before 
finishing tv/nd/ng. 



Pr/mary tvouncfonct 
toped ready for secorxfory 



Copperr/ODon 
Storting end of ty/'re 
ioldered ondtsucce^ulve 
turn3 ^ound o^er r/bboa 

Finidhlng endi 
^soldered. 



a 




=3 








r^^9 



I ^'9^ 



' starting e/)ds jo/dered 
ivoandj tv/res in mu/f^Cs 



One leg wifhprimory 
and ^econdorty finished 



Figs. 138 to 147 inclusive. — Details of the welding transformer 

prevents the annoyance of the first turn coming loose after 
i the winding is removed from the lathe. 

Over the first layer of the primary is placed a layer of 
press board and then the second layer of wire is wound 
until the 4Sth turn is reached. At this point a tap of cop- 
per ribbon is taken as shown in Fig. 143. Over this the 
winding is continued until the 90th turn is in place. This 
turn is soldered to the tip of a third piece of ribbon pre- 
viously placed so that the winding holds it. The same 



250 HIGH FREQUENCY APPARATUS 

procedure is repeated with the other core leg and two 
layers of press board fitted ready for the secondary 
winding. 

The secondary consists of 10 turns in all, five to each 
layer. The winding is composed of three No. 4 D.C.C. 
wires wound in multiple as shown in Fig. 146. The wire 
should be on three spools arranged conveniently in back of 
the operator who should wear canvas gloves in handling 
the heavy conductor. The wires will have to be tapped in 
place with a small wooden mallet, ^he starting ends are 
soldered to a piece of heavy copper strip, the winding done, 
and the finishing end secured in a similar manner. A sub- 
stantial covering of press board finishes the windings after 
they have been liberally painted with armalac or a similar 
compound. 

The legs with the windings on may then be set on end 
and the 3 by 6 pieces of steel inter-leaved in order to com- 
plete the magnetic circuit. One end of the core complete 
is shown in Fig. 139. A slight tapping with a light ham- 
mer will set up the irons. 

The Mounting. — The mounting is clearly shown in 
Fig. 148 as is also the directions of the windings. The 
builder should determine this very carefully by placing the 
cores end to end before assembling and then noting which 
terminals of the windings, when connected together, will 
produce a continuous winding in one direction throughout. 

The copper ribbon taps are soldered to No. 10 flexible 
stranded conductor on the primary and to three No. 4 flex- 
ible stranded cables in multiple on the secondary. The 
cables are lead to binding posts on the primary end and 
massive copper bolts on the secondary. The connections 
between the halves of the windings are made with strips 
of copper insulated with tape. 

Welding Experiments. — The current delivered by the 



CONSTRUCTION OF WELDIXG TRANSFORMER 



251 



transformer just described is of low voltage but great vol- 
ume. Such a current may be applied to the requirements 
of the popular science entertainer in a number of Avays and 
the space available in this treatise will permit of but a brief 
outline of the many interesting experiments it is possible to 
produce. 



r 




»5 



iff 



M 



iShovring d/recf/on 
of kv/ncf/ngs 




Fig. 148. — The transformer complete showing diagram of connections 

As a necessary adjunct to the transformer described 
previously may be mentioned a pair of heavy cables to 
conduct the current from the secondary of the transformer 
to the appliances with which the experiments are to be per- 
formed. Such cable may be purchased in an electrical sup- 
ply store, but it is likely to be rather too stiff for the re- 



252 HIGH FREQUENCY APPARATUS 

quirements of the performer. For this reason the author 
suggests that the worker make his own cable, and the 
appended illustration (Fig. 149) shows how this may be 
done. A coil of No. 24 bare copper wire is cut into suffi- 
cient ten-foot lengths to make up two bundles of wire each 
y^ inch in diameter when the wires are tightly bound to- 
gether. The end of one bundle of wires is forced into a 
substantial lug and very carefully soldered to insure that a 
perfect electrical connection is made. This lug is then 
gripped in a vise and the wires are stretched individually 
and collectively along the bench with the ends held securely 



f/nof ivropp/ng 
of f/jh line 




T 
^Wrop with cotton Bind ond solder 

fopQ tnfo luff 

Coble o Duncfle of ^^ ?-# bare copper n/ra ro form 

conduc/orj mch tfj/cA 



Fig. 149. — Showing construction of cable to carry the heavy secondary current 

when the stretching has been done. A wrapping of cotton 
tape is then wound throughout the entire length of the 
cable starting at the end with the lug and finishing tem- 
porarily three or four inches from the other end where the 
tape is bound with wire to keep it from unwinding. Again 
starting at the lug end, a layer of fi^e, hard fish line is 
wound around the cable and over the tape, finishing the 
covering of the cable. Before cutting the tape and line at 
the finishing end the wires are to be cut ofif squarely and 
inserted into a second lug which is carefully soldered as in 
the case of the ftrst one. The tape and line may then be 



COXSTRUCTIOX OF WELDING TRANSFORMER 



253 



brought up to the lug and finished off. The same process 
is repeated with the second bundle of wires to form a cable 
similar to the first. 

The only other adjuncts necessary for the simpler ex- 
periments with the transformer are two pairs of tongs or 
clamps to which the cables are fastened. In Fig. 12 the 
reader will note a suggestion for a pair of tongs of suit- 
able design, and if the worker is a fairly skilful pattern- 



Tongj or Copper 
or Bronze 




/ 
Smooth jam 



Fig. 150. — These copper tongs are useful in the conduct of many experiments 

alternating current 

maker he can make a pattern from which a copper or 
bronze casting may be made. Failing in this, he may use 
a dismantled pair of iron tongs or gas pliers for the pat- 
terns, making such changes as may be necessary with the 
aid of a bit of hard wax. The illustration is just one-half 
the size of the finished tongs used in the author's outfit, 
and it will not be safe to use a lighter weight of copper as 
the tongs heat up pretty well after the current has been on 



254 HIGH FREQUENCY APPARATUS 

a few minutes. The lug of the cable is fitted to the handle 
of the tong as shown in the illustration. 

Assuming that the transformer has been set up, the 
worker will be anxious to try it out. The tongs may be 
grasped with the bare hands as the voltage of the secondary 
is so low that practically no* shock will be perceptible; 
however, if the performer's hands are tender or susceptible 
to perspiration, the handles of the tongs may be dipped in 
white lacquer which will be quite invisible when dry but 
which, at the same time, acts as an effective insulator. 
The tongs having been connected to the transformer sec- 
ondary by means of the cables and the 60-cycle alternating 
current circuit through a 30-ampere fused switch, the per- 
former may grasp a piece of 54-i^^ch steel rod about two 
feet long in the jaws of the tongs and have an assistant 
turn on the primary current. The steel will quickly dis 
color and become gradually red and then white hot. A' 
this stage the current should be turned off and the per 
former should place a pair of gloves on his hands, explain- 
ing to the audience that, as they have just seen, the cur« 
rent passing through his hands has no effect whatever upon 
him, but that the intense heat so near his hands is worse 
than unpleasant. The heavy gauntlet gloves in place, the 
experiment can be carried to the stage of white heat, aA 
which point the steel is almost plastic and the rod can be 
bent easily into a U shape A few minutes more and the 
steel actually burns up in the performer's hands, sending 
forth a shower of sparks in all directions. In order to 
protect the eyes and clothing from the sparks, it is well to 
wear a helmet and a^ large leather apron to completely 
cover the person. This dress has its psychological effect 
upon the audience also. 

The transformer maj be used to weld together two 
pieces of iron rod held in tongs and brought together ; spot 



I 



CONSTRUCTION OF WELDING TRANSFORMER 255 

welding of sheet iron may be done if a device is built to 
provide sufficient pressure at the contracts ; a mass of metal 
may be brought almost to the melting point if placed in a 
crucible and the terminals inserted ; and, in fact, countless 
other expei"iments, many of which will suggest themselves 
to the possessor of the transformer, may be performed. 

A most effective stage setting is one of dark purple 
velvet in the form of a cavelike afifair. Practically all of 
the electrical experiments should be .performed in semi- 
darkness in order that the effect may be striking. The 
fusing of copper and zinc rods held in the tongs with the 
stage dark makes one of the most starting experiments the 
author has ever beheld. 



CHAPTER XXIII. 
HINTS FOR THE ELECTRICAL ENTERTAINER. 

Not the least important feature of the work in hand is 
the preparation of a suitable explanatory lecture to accom- 
pany the experiments which are to be performed with the 
apparatus described. Upon the snap and vigor of the lec- 
ture depend in a large measure the successful presentation 
of the ofifering. It is safe to assume that the day of the 
electrical fakir is past — no longer can the smooth-tongued 
performer claim some supernatural power which enables 
him to take through his body enormous voltages which 
would prove fatal to the average mortal. The lecturer of 
this type is as much a thing of the past as is the old-time 
magician who makes claim to some occult power rathei^ 
than to sleight-of-hand or mechanical ingenuity to accom-f 
plish his tricks. The electrical entertainer of to-day must 
bear in mind that in the past five years the education of the 
general public along the lines of electricity and science has 
advanced in an astonishing degree, and to offer his experi-I 
ments under the guise of a wizard is not only to insult the| 
intelligence of his audience, but to stamp himself as an 
absurd charlatan as well. Just as the modern prestidigi- 
tator credits his quickness of hand, so should the electrical 
entertainer give credit to modern science for his ability to 
perform the startling experiments he offers. 

Class of Audience. — The class of audience catered to 
should also bear careful consideration. The style of talk 
favored by the intelligent and well-read Chautauqua as- 

256 



HINTS FOR ELECTRICAL ZXTERTAINER 257 

sembly would be hopelessly out of place in even a high- 
class vaudeville theatre. This is not due to the lesser 
degree of intelligence to be found in the theatre audience 
so much as to the fact that. such an audience demands to 
be shov^n rather than told. The experiments must speak 
for themselves and any lecture accompanying their presen- 
tation must be more in- the nature of an explanatory 
''chatter" rather than a discourse on the theory and scien- 
tific reasons for the phenomena demonstrated. With the 
typical lecture audience; on the other hand, the explanatory 
remarks may be more comprehensive in nature, as such an 
audience comes to listen and be instructed, as wtW as to 
see and be entertained. At the same time the performer 
must not lose sight of the fact that many of the people in 
even a scholarly audience are totally unfamiliar with even 
the fundamentals of electricity except in a vague way, and 
his discourse should therefore be interspersed with fre- 
quent analogies in everyday life in order that the terms 

^and phrases used , may be clearly comprehended. 

I' A clever touch of comedy is of almost inestimable 

j value; for the theatre audience it should be of the ''slap- 
stick'' variety, w^hile for the lecture assernbly it should be 
genteel or even subtle in nature. As an illustration of the 
former style of comedy, the writer has seen many a 

jmediocre electrical act carried through to a riotous curtain 

.simply because a handful of boys from the audience were 
knocked oflF their feet supposedly through contact with a 

'wire. The same bit of comedy presented for the approval 

|0f a more cultured audience would have resulted in a few 

(disdainful smiles. 

Short Introduction Preferable. — The performer should 

beware of a lengthy introduction in either of the two cases. 
For the theatre, the opening remarks should be exceedingly 

Ibrief and "straight from the shoulder,'' for an audience of 



258 HIGH FREQUENCY APPARATUS 

this nature is ever impatient for something to happen and 
the quicker the action throughout the better the receptiom 
If the lecturer is endowed with an unusually commandmg 
presence, which invariably combines the gift of wit or 
humor, he may carry the action with his own magnetic 
personality; but for the individual who - -t gAe^ ^ 
?his manner, the rapid-fire style, is safer and less hkely to 
subject him to the disconcerting ridicule of an unruly gal- 

Iprv crowd. 

Impressive Opening Imperative-The introductory re- 
marks should be quickly followed up with an impressive 
experiment. ilfTs is- to at once arrest the attention and whe 
the appctit^for better things to come. After the successful 
completion of this one experiment, the performer has m 
a large measure, gained the confidence of h.s people, and 
in consequence, they will be the more ready to listen to 
his further remarks. At this point may come the real in- 
troduction to the entertainment to follow. The experi- 
ments should be placed on the programme m logical orde 
and every effort made to so arrange them that there shall 
be no wait whatever between the successive demonstrations. 
The mediocre experiments should be interspersed with 
the spectacular and startling ofles, and invariably the climax 
should consist of the one experiment that proves to be the 
masterpiece. It is not always possible to determine jus 
which one from among the number may properly lay clam 
to this title and this is where the value of trying it or^ th. 
^oc" comes in. As a matter of fact the final rehearsals of 



the performance should be before a real audience and . 
critical one at that, for only in this way can the productior 
be whipped into shape. 

Selection of Experiments.-The selection and prepara 
tion of the experiments to be used in his program mus 
needs rest with the entertainer himself. The work mus 



HINTS FOR ELECTRICAL ENTERTAINER 259 

show the individuality of the entertainer, since he is to 
perform the experimen-ts and is responsible for their recep- 
tion by the audience. The hints offered in this book 
should, therefore, be considered in the- light of suggestions 
only, and the most the writer can hope is that they will 
start the entertainer on the right track. Constant experi- 
ment day after day will serve to bring out the w^onderful 
possibilities in the apparatus, and as the worker proceeds he 
should make note of the effects produced and strive in fut- 
ure attempts to make^ the manner of presentation more 
striking and interesting. The one big thing to be borne in 
mind, as outlined in the last article, is that the experiments 
must hold the interest of the audience without the neces- 
sity of discourse or explanation. In the first place, the 
hio^h frequency discharge produces a deafening noise which 
in itself renders speech inaudible while the coil is in opera- 
tion, and, secondly, the audience as a rule does not care 
what the entertainer has to say and it must be shown. 
Simplicity should be the keynote throughout, for the aver- 
age theatre audience may be treated as a more or less un- 
ruly crowd of children who want solely to be amused and 
entertained. With these facts in mind, the entertainer may 
plan his program. The number of experiments is seem- 
ingly limitless when one starts to operate the apparatus, 
and as the time allotted the average feature act in vaude- 
ville is from twenty to thirty minutes, it is obvious that 
only the pick of the lot should be chosen. Some may be 
selected for their beauty, but the majority should be picked 
with a view to their sensational qualities. 

Probably the most effective opening number is pro- 
duced by the high frequency transformer in operation at 
full power with a dark stage. The streamers of fire leap 
out for several feet in all directions from the ball atop the 
transformer. The discharge makes a tremendous crackling 



260 HIGH FREQUENCY APPARATUS 

and crashing noise which impresses the audience through 
its weirdness even before the curtain rises. As the curtain] 
ascends, the center of the stage appears to be filled with a 
twisting, darting mass of slender, purplish fingers of fire 
which snap at the entertainer as he enters through the 
center door and walks down stage or toward the. footlights 
The current may, at this time, be shut ofif and the light 
turned on full for the opening remarks which were dis-j 
cussed in a preceding paragraph. . 

After the short preliminary address the performer may 
briefly explain to the audience how modern science enables 
man to make electricity his servant, and a servant whose 
services are to be respected but n6t feared. For instance, 
he can say that if he were to place his hands across the 
terminals of the low frequency transformer (pointing out 
the instrument, but not explaining its principles) he would 
receive a shock that would positively be fatal, since its 
voltage is in excess of that used in the electric chair. He 
may then go on^ to say that through a simple process of 
conversion which changes the nature ot the current but 
which does not in any way materially reduce its strength, 
and which, indeed, serves to increase its voltage to near or 
quite the millon mark, he is ena^)led to apply that erstwhile 
destructive force to the good of mankind, curing diseases, 
relieving pain and in countless other ways fulfilling the 
claim that electricity is man's greatest servant when in- 
telligently handled. The performer may then show how 
the tremendous current can be taken through the body 
without danger, even though its voltage is hundreds of 
times that used for purposes of electrocution. A metal rod 
is grasped in the hands, and while standing on an insulated 
stool the periFormer approaches the ball discharger of the 
transformer with the lights out and the coil in operation. 
As the rod nears the ball, a beautiful halo or luminous 



I 

e 

1 



HINTS FOR ELECTRICAL ENTERTAINER 261 

vapor gathers at the point and increases in intensity as the 
distance is shortened. 'Finally, when the rod is within four 
or five feet of the ball, an enormous sheet of purplish- 
white flame crashes across the intervening space and into 
the rod held in the hands. The spark leaps into the air 
and breaks as the heat causes it to rise, and the moment the 
discharge is broken another flame takes its place. If the 
distance is shortened to within six inches "or a foot of the 
ball, a piece of stick or bit of paper held in the spark will 
be ignited immediately.. 

The performer may then withdraw and have the cur- 
rent turned off for a few words of explanation. The next 
experiment may be made to show that the current is actu- 
ally going into the body of the entertainer. To this end, 
he approaches the ball with his rod held in one hand and 
in the other he grasps an electrode to which is connected 
a wire leading to one terminal of an incandescent lamp. 
The other terminal of the lamp is attached to a second 
electrode which is held by the assistant. When the cur- 
rent is turned on the spark leaps to the rod as before and 
the lamp is lighted to full incandescence or even burned 
out by the current passing between the bodies of the per- 
former and his assistant standing nearby'. 

Some of the most startling and spectacular experi- 
\ ments of which the high frequency apparatus is capable are 
1 produced in connection with the insulated stool and the 
charged body of the performer. For most of these experi- 
ments, the frequency of the current should be increased by 
moving the primary clip of the oscillation transformer to 
a point where fewer turns are included in the circuit. This 
will reduce the spark length of the coil, but this loss can 
be tolerated in view of the fact that the current is smoother 
and the muscular contractive effects are totally missing. 
It is difficult for the performer to do justice to his experi- 



262 HIGH FREQUENCY APPARATUS 

merits if he experiences any degree of shock, which, while 
not at all dangerous, is still disconcerting. 

The performer stands on the stool and touches the 
discharge ball of the 'coil with his metal wand. When th( 
current is turned on, a strong, snapping spark several inches 
in length may be drawn from any portion of the body bj 
the assistant. This spark will . ignite a piece of cottor 
dipped in alcohol, light a cigarette, puncture a thin piece 
of glass, and do many other equally interesting tricks. I 
the spark is taken from the bare ski^ for any length of time, 
a blister will form from the burn which results, and it is 
therefore advisable- to draw the spark from a heavy rin^ 
worn on the performer's free hand. An occasional spark 
taken for' a few seconds at a time will not affect the skin 
and the lighting of the cotton may be accoriiplished by the 
assistant bringing the material in close proximity with the 
performer's ear or chin. Care should be taken to avoid sparks 
near the eyes. If the performer holds a metal spoon in his 
mouth, a spark ,may be drawn from the handle and this 
experiment seMom fails to bring applause. 

If the primary clip on the oscillation transformer is 
carefully adjusted after the performer has been connected 
with the discharge ball, a poirtt will be found where his 
body seems literally to exude a luminescent halo of bluish 
white fire. When the free hand is raised directly over the 
head, little tongues of fire dart from the finger tips into 
the air. When a second person approaches to within a 
foot or so of the performer the space between their bodies 
is apparently filled with a luminous vapor* and a finger 
pointed at the performer instantly calls forth an intense, 
cone-shaped stream of light. A Geissler or other vac- 
uum tube brought to within even six or eight feet of the 
charged body lights up with its characteristic glow, and, 
when it approaches to within a foot of the body, the glow 



HINTS FOR ELECTRICAL ENTERTAINER 263 

is practically as bright as it would be if the current were 
passing into it through a wire instead of through space. 

An entertaining experiment is to bring an incandescent 
lamp bulb, held by its base in the assistant's hand, close to 
a rod held in the hand of the performer. The current 
slowly strikes through the glass wall, and, as the fracture 
increases, the air is let into the bulb. As the vacuum 
lowers the color of the glow in the bulb changes from 
bluish white to red, then to purple and finally it disappears 
as the spark punctures the wall and finds its way to the 
wires inside. 

No further attempt will be made to describe *'experi- 
ments'' for to do so is futile at this point. The worker will 
find that every time he turns the current on, he finds some 
new wrinkle or stunt to do with the spark. Ardent experi- 
mentation with the apparatus itself is the very best teacher 
and a day spent merely in ''playing" with the outfit will 
give the ingenious worker scores of fascinating experi- 
ments, some of which are suitable for the stage and others 
for the parlor or the laboratory. 

Dr. Tesla prepared a series of intensely interesting lec- 
tures some years ago and his work, now in book form, 
offers a truly remarkable series of instructive experiments. 
While Dr. Tesla advocates, in his book, the use of a high 
frequency alternator or else an oil-immersed oscillation 
transformer, still many, if not all, of the performances he 
pictures can be shown with the apparatus described in ^is 
book. 



264 



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INDEX 



Alternating Current 15 

Alternative Current, period 

of . 16 

Alternators 17 

Ammeter, Hot Wire 160 

Apparatus, Electro - thera- 
peutic 127 

Apparatus, Induction Coil... 71 

Apparatus, installation 6i . . 198 

C 

, Cabinet 152 

'( Characteristics of Hi^h Fre- 
quency Current 20 

, Circuits, Oscillatory 34 

I Coil Construction, Induction 74 

^ Coil, Oudin .* 151 

Coils, Induction 47 

Coils, Kicking . . . : 48 

Coils, Proportion of 63 

Coils, Tesla 106 

Condenser 31 

Condenser Discharg^i Gen- 
erator 28 

Condensers, High Potential 49 

Condensers, Mica 53 

Condensers, Moulded . . ; . . 53 
Conductive Electrical Enter- 
tainments 256 

Connection . . . . , 158 

Connections Ill 

Construction of Large Ap- 
paratus 218 

] Construction of Spark Gap 190 



Core 101 

Core Volume Transformers 41 
Cultivation, .High Fre- 
quency Current 182 

Culture, Plant 172 

Current 29 

Current, Alternating 15 

Current, High Frequency , . 19 
Cycle . ..' 16 

D 

D'Arsonval Oscillation 

Transformer 143 

Data, Transformer 264 

Design of Induction Coils.. 47 

Design of Transformers. . . 40 

Direct Current Outfits 129 

E 

Electrical Apparatus for the 

Stage 212 

Electrical .Entertainments, 

Conducting 256 

Electroculture Methods . . . 173 
Electro-Therapeutic Outfits, 

Operation of 166 

Electro-Therapeutic Work.. 98 
Experiments, Selection of.. 258 
Experiments, Welding .... 250 

F 

Frequency of Generators.. 17 

G 

Gap, Quenched Spark 56 

Gap, Rotary 55 

267 



268 



INDEX 



Generation of Ozone 23 

Generation of X-Rays .... 23 

H 

High-Frequency Current . . 19 
High - Frequency Current, 

Characteristics of 20 

High - Frequency Current 
Cultivation . ............ 182 

High - Frequency Current 

in Medicine 22 

High Potential Condensers 49 
High Potential Tesla Cur- 
rent 170 

High-Potential Transformer 31 

Hot-Wire Ammeter 160 

How High-Frequency Cur- 
rent is Produced 27 

I 

Improvised Winding Ma- 
chine 148 

Inclosed Spark Gap 230 

Induction Coil Apparatus.. 71 

Induction Coil Construction 74 

Induction Coil Design .... 47 

Induction Coils 47 

Installation of Apparatus.. 198 

Insulation, Secondary .... 66 

Interrupter 80 

K 

Kicking Coil Apparatus.... 85 
Kicking Coil Method of 
Producing High - Fre- 
quency • 29 

Kicking Coil Outfit 126 

Kicking Coils 48 

L 

Large Apparatus, Construc- 
tion of 218 

Large Portable Outfits 130 

Large Tesla Coils 239 



M 



1 



Magnetic Leakage Trans- 
former 36 

]\Iica Condensers 53 

' ^lotor-Generators 18 

Aloulded Condensers 53 

N 

N<!>tcs on Plant Culture 204 

Number of Poles on Gener- 
ators I . . . . 17 

O 

Office Equipment Made 

with Standard Materials. 145 
Office Equipment, Physi-.... 

cians ' 132 

Operation of Electrothera- 

peutic Outfits 166 

Oscillatory Circuits 34 

Oscillation ' Transformer .. 31 
Oscillation Transformer, 

D'Arsonval 143 

O.udin CoiL 61 

Oudin Resonator 245 

Outfit, Kicking Coil 126 

Outfits, Direct Current ... 129 
Ozone, Generation of 23 

P 

Period of A. C. Current .. 16 
Physician's Portable Appar- 
atus 125 

Plant Culture 172 

Plant Culture, Notes on . . . 204 

Plot, Wiring . . 201 

Poles, Number on Genera- 
tors 1/^ 

Portable Apparatus, Physi- 
cians 125 

Portable Outfits, Large ... 130 

Primary Winding 101 

Proportions of Coils 63 



INDEX 



269 



Quenched - Gap Traus- 
formers 121 

Quenched Rotary Spark 
Gap 58. 

Quenched Spark Gap ...*. 56 

R 

Resonator, Oudin 245 

Rotary Gap 55 

' Rotary . Quenched Spark 
Gap 58 

S 
■ Secondary Insulation 66 

Secondary Winding • 11 

^Setting Up Stage Apparatus 236 
,Soft Iron Cores, Weight of 

,) (Table) ' 266 

^Spark-Gap ^ * 31 

'Spark-Gap, Construction of 190 

Spark-Gap Stationary .... 140 
'^Stage, Apparatus for 212 

Stage Apparatus, Sef.ting up 2>36 
^^Stationary Spark-Gap .... 140 

T - 

p,Table (Turns per Linear 

\ Inch) 265 

iTable (Weight of Soft Iron 

Cores) \ 266 

esla Coils 106 



r 



Tesla Coils, Large 239 

Tesla Current, High-Poten- 
tial 170 

Transformer Data 264 

Transformer Design 40 

Transformer, Magnetic 

Leakage T3'pe 36 

Transformer, Vacuum Tube 

Oscillation ♦ 142 

Transformers, Quenched- 

Gap 121 

Turns per Linear Inch 
(Table) ' 265 

V 

Vacuum Tube Oscillation 
Transformer v 141 

Volume of Cone, Trans- 
formers 41 

W 

Weight of Soft Iron Cores 

(Table) 266 

Welding Experiments .... 250 
Winding Machine, Impro- 
vised 148 

Winding, Primary 101 

Winding, Secondary 11 

Wiring Plot 201 

X 

X-Rays, Generation of . . . 23 



1920 

REVISED ■ • 

CATALOGUE 

of the Latest and Best 

Practical and Mechanical Books 

Including Automobile and Aviation Books 




PRACTICAL BOOKS FOR PRACTICAL MEN 

Each Book in this Catalogue is written by an 
Expert and is written so you can understand it 



PUBLISHED BY 

The Norman W. Henley Publishing Co. 

2 West 45th Street, New York, U. S. A. 

Established 1890 
Any Book in this Catalogue sent prepaid on receipt of price 



INDEX 



Air Brakes 

Arithmetic , 1J5, 

Automobile Books 3, 

Automobile Charts , 

Aviation , 

Aviation Chart , 

Bevel Gectr 

Brazing 

Cams 

Carburetors t . . . . i . . , 

Change Gear 

Charts 

Coal 

Coke 

Combustion 

Compressed Air 

Concrete 11, 12 

Cosmetics 

Dictionary > . . . . 

Dies 

Drawing 15, 

Drop Forging 

Dynamo Building* 

Electric Bells 

Electric Switchboards 

Electric Toy Making 

Electric Wiring .* 

Electricity 16, 17, 18, 19, 

Electroplating 

** Everyday Engineering " 

Factory Management 

Ford AutomoLile 

Ford Trouble Chart 

Formulas and Recipes *. 

Fuel 

Gas Engine Construction 

Gas Engines 

Gas Tractor 

Gearmg and Cams 

Heating * 

High Frequency Apparatus 

Horse Power Chart 

Hot Water Heating 

House Wiring 

Hydrauhcs 

Ice - .^ 

Interchangeable Manufacturing . . . . 

Inventions 

I^ots 

Lathe Work 

Link Motions 

Liquid Air ^ 

Locomotive Boilers ; 

Locomotive Breakdowns 

Locomotive Engineering. . . .26, 27, 



PAGE 

.26, 29 

30. 40 

4, 5,6 

. 6, 7 

.6,7, 8 

6 

24 

8 

24 

5 

24 

,6,7, 9 

22 

11 ' 

27 

11 

,13,14 

35 

14 

14, 15 

16,36 

15 



17, 



16 
20 
19 
17 

18. 19 

20,21 
21 
30 
21 
3 
10 
37 
22 
23 

22, 23 
42 
24 
40 
20 
39 

40, 41 
18 
24 
24 
29 
25 
25 

25, 26 
27 
26 
27 
27 

28, 29 



PAGI 

Machinist Books 29. 30, 31, 32, 3J 

Manual Training 3-^ 

:^larine Engineering S,' 

Ivlarine Gasohne Engines 2i 

Mechamcal Drawing l( 

Mechanical Movements. .• 31 

Metal Work 14,1.' 



Mining 

Mo^lel Making 

Motor Boats 

IMotorcycies 

Patent^ , 

Pattern Making ......* 

Perfumery 

Perspec^vi ve 

Plumbing 36, 

Producer Gas ^. 

Punches 

Radio ^ 

Railroeid Accidents * 

Railroad Ctjarts 

Recipe Book 

Refrigeration 

Rubber Stamps 

Saw FiUng ! 

Saws, Management of 

Sheet Metal Works '. 14. 

Shop Tools . . . , 

Sketching Paper 

Soldering 

Steam Engineering 39, 

Steam Heating 40, 

Steel 41, 

Storage Batteries 

Submarine Chart 

Switch Boards 17, 

Tapers 

Telegraphy, Wireless 

Telephone .• 

Thread Cutting 

TcTol Making 

Toy Making 

Tractive Power Chart 

Tractor, Gas . ., 

Trail) Rules 

Turbines 

Vacuum Heating *. 

Valve Setting 

Ventilation 

Walschaert Valve Gear 

Waterproofing 

Welding 

Wireless Telegraphy'. . 19, 

Wiring 18. 

Wiring Diagrams 



Any of these books promptly sent prepaid to any addresf 

in the world on receipt of price. 

How to remit. — ^By Postal Money Order, Express Money Order 

Bank Draft or Registered Letter. 



CATALOGUE OF GOOD, PRACTICAL BOOKS 



AUTOMOBILES AND MOTORCYCLES 

HE MODERN GASOLINE AUTOMOBILE— ITS DESIGN, CONSTRUC- 
TION, MAINTENANCE AND REPALR. By Victor W. Page, M.E. 
The latest and most complete treatise on the Gasohne Automobile ever'issued. WritteD 
in simple language by a recognised authority, famihar with every branch of the au'co 
mobile industry. Free from technical terms. Everything is explained so simply 
that anyone of average intelligence may gain a comprehensive knowledge of the 
gasohne automobile, i'he information is up-to-date and includes, in addition to an 
exposition of principles of coustruct**jn and description of all types of automobiles and 
their components, valuable money-saving hints on t&e care and operation of motor- 
cars propelled oy interaal combustion engines. Among some of the subjects treated 
might be mentio^ned : Torpedo acd other symmetrical body forms designed to reduce 
air resistance; sleeve valve, rotary valve and other types of silent motors; increasing 
tendency to favor worm-gear power -transmission : universal application of magneto 
ignition; development of automt)bil9 electric-hghting systems; block motors; under- 
slung chassis; application of practical self-starters; long stroke and offset cylinder 
motors; latest automatic lubrication systems; silent chains for valve operation and 
change-speed gearing; the use of front wheel brakes and many other detail refinements. 
By a careful stjidy of the pages of this book one can gam practical knowledge of auto^ 
mobile construction that will savC' time, money and worry. The book tells you just 
what to do. how and when to do it. Nothing has been omitted, no detail has been 
shghted. Every part of the automobile, its equipment, accessories, tools, supplies, 
spare parts necessary, etc., have been discussed comprehensively. If you are or 
intend to become a motorist, or are in any way interested in the modem Gasoline 
Automobile, this is a book you cannot afford to be without. Over 1,000 pages — • 
and more thf»,n 1,000 new and specially naade detail illustrations, as well as paany full- 
page and double-paoce plates, showing all parts of the automobile. Including 12 large 
folding plates. 1920 Edition. Price $4.00 

WHAT IS SAID OF THIS BOOK: 

I "It is the best book ot\ the Automobile seen up to date." — J. H. Pile. Associate Editor 

{Automobile Trade Journal. 

i "Every Automobile Owner has use for a book of this chantcter." — The Tradesman. 

"This book is superior to any treatise heretofore published on the subject." — The 

Inventive Age. 

"We know of no other volume that is so complete in all its departments, and in which 
(the wide field of automobile construction with its mechanical intricacies is so plainly 
i handled, both in the text and in the matter of illustrations." — The Motorist. 

"The book is very thorough, a careful examination failiiig to disclose any point in 
I connection with the automobile, its care and repair, to have been overlooked." — 
ijron Age. 

"Mr. Page has done a great work, and benefit to the Automobile Field." — W. C. 
'Hasford, Mgr. Y. oM. C. A. Automobile School, Boston, Mass. 

['"It is just the kind of a book a motorist needs if he wants to understand his car." — 
[iAinerican Threshc-rman. 

\e model T ford car, ITS CONSTRUCTION, OPERATION AND 
REPAIR, INCLUDING THE FORD FARM TRACTOR. By Victor W. 
Page, M.E. 

' This is a complete instruction book. All parts of the Ford [Model T Car are described 
.and illustrated; the construction is fully described and operating principles made 
clear to everyone. Every Ford owner needs this practical book. You don't have to 
guess about the construction or where the trouble is. as it shows how to take all parts 
apart and how to locate and fix all faults. The writer, ]Mr. Page, has operated a Ford 
icar for four years and writes from actual knowledge. Among the contents are: 
1. The Ford Car. Its Parts and Their Fimctions. ?. The Engine and Auxihary 
Groups. How the Engine Works — The Fuel Supply System — The Carburetor — 
{Making the lenition Spark — Coohng and Lubrication. 3. Details of Chassis. 
Change Speed Gear — Power Transmission — Differential Gear Action — Steering Gear 
— Front Axle — Frame and Springs — Brakes. 4. How to Drive and Care for the Ford. 
'The Control System Explained — Starting the ISIotor — Driving the Car — ^Locating 
Roadside Troubles — Tire Repairs — Oihng the Chassis — Winter Care of Car. 5. Sys- 
tematic Location of Troubles and Remedies. Faults in Engine — Faults in Carbure^r 



CATALOGUE OF GOOD, PRACTICAL BOOKS 



TffTiition Troubles— Cooling and Lubrication System Defects— Adjustment oil 
TraWission G^ear^::?Genera^ Chassis Repairs Tl«. Ford Tractor and Tractor conj 
vprsion sets and Genuine Fordson Tractor Operation and Repair— FA. btartmsl 
Ini uihtLi%^stem. 153 iUustrations. 410 pages. Two large folding p^atgsl 

Price ; ^ ij>*^.w.| 

AUTOMOBILE REPAIRING MADE EA8Y. By Victor W. Page, M.E. 
A comnrehensive practical exposition of every vh^^ of modem automobile repairir 
nracS^- OutU^^^^ every process incidental to motor car restoration. Gives plans f. 
workshoD constmction suggestions for equipment, poAver needed, machinery and too 
^Poessa?? to car^ or{ thrb'Isiness successfully. TeUs how to overhaul and repair . 
nnrffof all aXmobiles Every tiling is explained so simply that motorists and studen 
can acoSre a fXwo^^^^^ knc>w]edge of automobile repairing. Th s work starts wii I 
the enliSf then consider^ carburetion, ignition, coohng and lubrication systems 1 ^^ 
rhitch change speed goaring and transmission system are considered in detail. Contain 
hi^lmctioS^^for rep^^^ all types of axles, steering gears and ether chassis part^ 
Many Ss shS^^ flguring and rules of practice .arc given for the mechanic 

Explains fully valve and magneto timing, -tuning" engmes systematic location c 
UouW<^ repair of ball and roller bearings, shop kinl^s, first aid to mjured and a multi 
tude of subjects of interest to all in the garage and repair business. 
Thj^ hnnk contains svecial instructions on electric starting, lighting and ignition systern: 

steel latest timing practice, eight and twelve-cylmdir motors, etc. 5^x8. Cloth. 10. > 
pages, 1.000 illustrations, 11 folding plates. Price J>^-^ 

WHAT IS SAID OF THIS BOOK : 

•« • AntrkTYinhilp RenairiuK Made Easy ' is the best book on the fubject I have ever so- 
and tl^Z]?y bookTevef s^^^^^^^^ any value in a garage. "-Fred Jeffrey. Martm. 

burg Neb. ■* • 

-I wish to thank you for sending me a copy of 'Automobile Repairing IMade Easy/ 
do nS thSijf it could be excelled "—S. W. Gisriel, Director'of Instruction. Y. M. C. A 
Philadelphia, Pa. 
QUESTIONS AND ANSWERS RELATING TO MODERN AUTOMOBIL 
CONSTRUCTION, DRIVING AND REPAIR. By Victor W. Page, M.l 
A practical self-instructor for students, mechanics and motorists, consisting of thirt. 
se?eTl4sons in tS^^ of questions and answers, written with special reference to tl 
rSemlntI of the non-technical reader desiring easily understood,. explanato, 
matterTelating to all branches of automobiUng. The subject-matter is absoliit 
S?re?t Sid explained in simple language. If you can't answer aU of the folio wii 
auSons you need thi^ work. The answers to these and nearly 2000 more are 
b^foun^ in its pages, 'oive the name of aaM important parts of an automobile a 
dtscXe their f£n?tions? Describe action of latest types of kerosene carbureto 
What is the difference between a "double'' ignition system and a- dual ignitu 
system? Name parts of an induction coil? How are, valves timed? _^ hat is c 
electric motor starter and how does it work? What are advantages of worm dri 
gearing? Name all important types of baU and roller bearings? What is a tnre 
ISrter" floating axle? What is a two-speed axle? ^. What is the.- Vulcan electric go 
shift? Name the causes of lost power in automobiles? Describe all noises aue 
deranged mechanism and give causes? How can you adjust a carburetor by . 
color of the exhaust gases? What causes "popping " m the carbiiretor? What t; 
and supplies are needed to equip a car? How do you drive various snakes otCc 
What is a differential lock and where is it used? Name different systems of y 
wheel construction, etc., ef c. A popular work at a popular prtce. ^ 5 >i x / >^. ^ ^ ; 
700 pages, 350 illustrations, 3 folding plates. Price 5>*i- 

WHAT IS SAID OF THIS BOOK: 
*'If you own a car — get this book." — The Glassworker. 

"Mr. Page has the faculty, of making difficult subjects plain and understandable. 
Bristol Press. ' 

••We can name no writer better quahfied to prepare a book of instruction on au^|| 
mobiles than Mr. Victor W. Page." — Scientific American. 
"The best automobile catechism that has appeared." — Automobile Topics. 
• "There are few men, even with long experience, who will not ^^^ this book usrf 
ereat pains have been taken to make it accurate. Special recommendation must 



CATALOGUE OF GOOD, PRACTICAL BOOKS 

given to the illustrations, which have been made specially for the work. Such ex- 
cellent books as this greatly assist in fully understanding your automobile." — En- 
gineering News. 

MODERN STARTING, LIGHTING AND IGNITION SYSTEMS. By Victor 
W. Page, M.E. 

This practical volume has been written with special reference to the requirements of, the 
non-technical reader desiring Easily understood, explanatory matter, relating to all 
types of aut(5mobile ignition, starting and ligliting systems. It can be understood by 
anyone, even without electrical knowledge, because elementary electrical principles are 
considered before any attempt is made to discuss features of the various systems. 
These basic principles are clearly stated and illustrated with simple diagrams. All the 
leading systems of starting, lighting and ignition have been dtscribed and illustrated with 
the co-operation of the experts employed by the manufacturers. Wiring diagrams are 
shown in .both technical and noa-technical forms. All symbols are fully explained. It 
is a comprehensive review of modern starting and ignition system practice, and includes 
a complete exposition of storage battery construction, care and repair. All types of 
starting motors, generators, ms^gnetos, and all ignition or lighting system units are 
fully explained. The systems of cars already in use as well as those that are to come 
in 1920 are considered. Every person in the automobile business needs this volume. 
; 5^x73^. Cloth. 804 pages, 492 iUustrations, 3 folding plates. Price . . $3.00 

GASOLINE AND KERO.SENE CARBURETORS, CONSTRUCTION, IN- 
STALLATION AND ADJUSTMENT. By Major Victor W. Page. A 
New Up-to-date Book on Modern Carburetion Practice. 

This is a simple, comprehensive, and authoritative treatise for practical men ex- 
plaining all.'^asic principles pertaining to carburetion. showing how Uquid fuels are 
vaporized and turned into gas for operating all types of internal combustion engines in- 
tended to operate on vaF<:)rs of gasohne, kerosene, benzol, and alcohol. All leading types 
of carburetors are described in detail, special attention being given to the forms de\'ised 
to use the cheaper fuels such as kerosene. Carburetion troubles, fuel system troubles, 
carburetor repairs and installation, electric primers and economizers, hot spot mani- 
folds and all modr.!Ti carburetor developments are considered in a thorough manner. 
Methods of adjusting all types of carburetors are fully discussed as well as sugges- 
tions for securing maxi-uium fuel economy and obtaining liighest engine power. 
This book is invaluable to repairmen, students, and motorists, as it includes the 
most complete exposition on kerosene carbiu-etors ever pubUshed. The drawings 
showing carburetor construction are made from accurate engineering designs and 
show all parts of late cy pes of carburetors. 250 pages. 89 illustrations. . $2.00 

fOW TO RUN AN AUTOMOBILE-. By Victor W. Page. 

This treatise gives concise instructions for starting and running all makes of gasoline 
automobiles, how to care for them, and gives distinctive features of control. De- 
scribes every step for sliifting gears, controlhng engine, etc. Among the chapters 
contained are: I. Automobile Parts and Their Functions. II. General Starting 
and Driving Iristructions. III. Typical 1919 Control Systems — Care of Auto- 
mobiles. Thoroughly illustrated. 178 pages. 72 iUiistrations. Price . . $1.50 

HE AUTOMOBILIST'S POCKET COMPANION AND EXPENSE RECORD. 
By Victor W. Page. 

This book is nxjt only valuable as a convenient cost record, but contains much in- 
formation of value to motorists. Includes a condensed digest of auto laws of all 
States, a lubrication schedule, hints for care of storage battery, and care of tires, 
location of road troubles, anti-free/inj? solutions, horse-pover table. dri\ing hints 
and many useful tables and recir es of interest to all motorists. Not a technical 
book in any sense of the word, just a coliection of practical facts in simple language 
for the every-day motorist. Con\eniont pocket size. , Price $1.25 

lUTOMOBILE WELDING WITH THE OXY-ACETYLENE FLAME. By 

I M. Keith Dunham. 

Explains in a simple manner apparatus to be used, its care, and how to construct 
necessary shop equipment. Proceeds then to the actual welding of all automobile 



CATALOGUE OF GOOD, PRACTICAL BOOKS 

I>arts, in a manner understandable by everyone. Gives principles never to be f oi ^ 
gotten. This book is of utmost value, since the perplexing problems arising whei I^ 
metal is heated to a melting point are fully explained and the proper methods t« 
overcome them shown. 167 pages. Fully illustrated. Price $1.6( 

MOTORCYCLES AND SIDE CARS, THEIR CONSTRUCTION, MANAGE 

MENT AND REPAIR. By Victor w! Pack, M.E. 

The only complete work published for the motorcj'clist and repairman. Describe 
fully all leading types of machines, their design, construction, maintenance, operatioi 
and repair. This treatise outlines fully the operation of two- and four-cycle powr 
plants and all ignition, carburetion and lubric5,iion systems in detail. Describes a I 
representative types of'irec 6ngine clutches, variable speed goal's and power trans 
mission syst/cms. Gives complete instructions for operating and repairing all typc^ 
Considers fully electric self-starting and lighting fvstems, all typos of spring frame 
and spring forks and shows leading control methods. For those desiring tcchnicu 
information a complete seri:>s of tallies and many formulo to assist in dt signing an 
included. The work tells how to figure power ne^od to climb grades, ovefcome ai 
resistance and attain high speeds. It shows how to select gear ratios for varioi: 
weights and powers, how to figure braking efficiency required, gives sizes of bcUs an; 
chains to transmit power safely, and shows how to design sprocK'ots, belt pr.llcys, etc 
This work also includes complete formul t^ for figuring horse-power, /hows how dyna 
mometer tests are made, defines relative efTlcionry 61' air- and water-cool; d en; ines. j^la^i 
and anti-friction bearings and many other data of a' practical, helpful, enginoerir; 
nature. Remember that you get this informntion in addition to tlio practical d 
scription and iftstructions which alone ai*o wortli several times the price of the boo-; 
600 pages. 400specially made illustrations, 4 folding plates. Cloth. Price . ^3.0C 

WHAT., IS SAID OF TH^S BOOK: i 

*' Here is a book that should be in the cycle repairer's klt/'x— American Blacksmith. 
" The best way for any rider to thoroughly understand his machine, is to get a cop^ 
of this book; it is worth many times its price." — Pacijic Motorcyclist. 

AUTOMOBILE, AVIATION AND MOTORCYCLE CHARTS 

AVIATION CHART— LOCATION OF AIRPLANE POWER PLANT TROUBLES 
MADE EASY. By Major Victou W. Page, AS., S.C.U.^S.li. 

A large chart outlining a^'il parts of a typical airplane power plant, showing the point. 
where trouble is apt to occur and suggesting remedies for the common defects. In 
tended especially for aviators and aviation mecha.iics on school and field duty 
Price ^ 36 centj 

CHART. GASOLINE ENGINE TROUBLES MADE EASY— A CHART SHOW 
ING SECTIONAL VIEW OF GASOLINE ENGINE. Compiled by Vieroi 
W. Page, M.E. 

It shows clearly all parts of a typical four-cylinder gasoline engine of the four-cyclt' 
type. It outlines distinctly all parts liable to give trouble anil also details the do« 
rangements apt to interfere with smooth engine operation. » ' 

Valuable to students, motorists, meclianics, repairmen, garagemen, automobile saleai 
men, chauffeurs, motorboat owners, motor-truciv and trav tor drivers, aviators, motori 
cycUsts, and all others who have to do with gasohne power plants. . 

It simphfles location of all engine troubles, and while it '.vill prove invaluable to tla 
novice, it can be used to advantage by the more export. It sliould be o i the walls d 
every public and private gar??/2;e. automobile repair shop, f'l.vy lious > pr school. It c.'^fl 
be carried in the automobile or pocket with easL\ and will insurj against loss of timi 
when ene^ine trouble manifests itself. 

This sectional view of engine is a complete review of all motor trou>ile<;. It is nrepan 
by a practical motorist for all who motor. More information for the money than ev 
before oflerecj. No details omitted. Size 25x3S inches. Securely mailed on rec6ii 
of 85 cen 



CATALOGUE OF GOOD, PRACTICAL BOOKS 

:HART. location of FGRD engine troubles made easy. Com- 
piled by Victor W. Page, M.E. 

This shows clear sectional views depicting all portions of the Ford power plant and 
auxiliary groups. It outlines clearly all parts of Uh* engine, fuel supply systern, igni- 

1 tion group and cooUng system, that ar/j apt to give trouble, detailing all dei'angements 
that are liable to mai^e an engine lose power, start hard or work irregularly. This 
chart is valuable to students, cT.vners, and drivers as it simplifies location of all engine 
faults. Of fereat advantage as an instructor for the no\dce, it can be used equally well 
by the more expert as a work of reference and review. It can be carried in the tool- 

. box or pocket with ease and ^ill save its cost in labor eliminated the first time engine 
trouble manifests itself. Prepared with special reference to the average mans needs 
and is a practical review of all motor troubles bcceuse r? is based on the actual ex- 
perience of an automobile engineer-mechanic with the mechanism the chart describes. 
It enabl^^s the ^non-technical ojvner or operator of a Ford car to locate engine de- 
rangements by systematic search, guided by easily recognized symptoms instead of by 
guesswork. It makes the average o^vner independent of the roadside repair shop 
when touring. JMust be seeih to be appreciated. Size 25x38 inches. Printed on 
heavy bond paper. Price 35 cents 

IHART. LUBRICATION OF THE MOTOR CAJi CHASSIS. Compiled by 
Victor W/Page, M.E. • - 

This chart presents the plan view of a typical six-cyhnder chassis of standard design 
and all parts are clearly indicated that demand oil, also the frequeD^y with which they 
must be lubricated and the kind of oil to use. A practical chart for aU interests in 
motor-car maintenance. Size 24x38 inches. Price 85 cents 

IHART. LOCATION OF CARBURETION TROUBLES MADE EASY. Com- 
piled by Victor W. Page, M.E. 

This chart shows all parts of a typical pressure feed fuel supply system and gives 
causes of trouble, how to locate defects and means of remedying them. Size 2-4x38 
inches. Price 35 cents 

^IHART. LOCATION *0F IGNITION SYSTEM TROUBLES MADE EASY. 

Compiled by Victor W. Page, M.E. 

In this diagram all pants of a typical double ignition system using battery and magneto 
current are showa, and suggestions are given for readily finding ignition troubl^ and 
eliminating them when found. Size 2-4x38 inches. Price 35 cents 

{hart, location of cooling and lubrication system FAULTS. 

d Compiled by Victor W. Page, M.E. 

This composite diagram shows a typical automobile power plant using pump circulated 
water-cooUng system and the most popular lubrication method. Gives susrgestions 
for curing all overheating and loss of power faults due to faulty action of tlie oihng 
or coohng group. Size 24x38 inches. Price 35 cents 

[^HART. LOCATION OF STARTING AND LIGHTLNG SYSTEM FAULTS. 

The most complete chart yet demised, showing all parts of the modem automobile 
startmg, lighting and ignition systems, gi-s-ing instructions for systematic location of 
all faults in wiring, lamps, motor or generator, switches and all other imits. Invalu- 
able to motorists, chauflem's and repairmen. Size 24x38 inches. Price . 35 cents 

HART. MOTORCYCLE TROUBLES MADE EASY. Compiled by Victor 
W. Page, M-E. 

A chart showing sectional ^iew of a sinarle-cylinder gasohne engine. This chart 
simphfies location of all power-plant troubles. A single-cylinder motor is shown for 
simplicity. It outlines distinctly all parts hable to give trouble and also details the 
derans:ements apt to interfere with smooth ensine operation. This chart will prove 
of valtie to all who have to do with the operation, repair or sale of motorcycles. No 
details omitted. Size 30x20 inches. Price 35 cents 



CATALOGUE OF GOOD, PRACTICAL BOOKS 



AVIATION 

A B C OF AVIATION. By MkjOR Victor W. Pag6. 

This book describes the basic principles of a^iatioci, tells how a balloon or dirigible 
is made and why it floats in the air. Describes how an airplane ties. It shows iu 
detail the different parts of an airplane, what they are and what tliey do. Describe; 
all types of airplanes and how they differ in construction; as well as detailing the 
advantages and disadvantr.ges of different types of aircraft. It includes a complett 
dictionary of aviation tiprms.,and clear drawings of leading airplanes. The reader 
will find simple instructions for unpacking, setting up, and rigging airplanes. ,\ 
full description of airplane control principles is given and methods of flying are dis- 
cussed at length. * 

This book answers every question one can ask about modem aircraft, their con- 
struction and operation. A self-educator on aviatiDn without an equal. 275 paget 
130 specially made illustrations with 7 plates. I'rice $2.5C 

AVIATION ENGINES— DESIGN; CONSTRUCTION; REPAIR. By Majou 
Victor W. Pag^:, A.S., 8.C.U.S.R. 

This treatise, ^ritten by a recognized authority on all of the practical aspects ol 
internal combustion engine construction, maintenance, and repair, fills the need as 
no other book does. The matter is logically arranged: all. descriptive matter is 
simply expressed and copiously illustrated, so that anyone can understand airplane 
engine operation and repair even if without jiirevious mechanical training. This 
work is invaluable for anyone desiring to liecome an aviator or aviation mechanic. 
The latest rotary types, such as the Gnome Monosoupapi^. and Lelihone, are fully 
explained, as well as the recently develoi)ed \ce and radial types. The subject^ 
of carburet! on, ignition, cooling, and lul)rication also are covered in a thorough manner 
The chapters on repair and maintenance are distinctive and found in no other book 
on this sul)ject. Not a technical }K)ok, but a practical, easily understood work ol 
reference for all interest^ed in aeronautical science. 576, pages. 253 illustrations.^ 
Price, net $3.0af 

GLOSSARY OF AVIATION TERMS — ENGLISH-I^RENCH; FRENCH^ 
ENGLISH. By Major Victor W. Page, A.S., S.CU.S.ll., and Lieut 
Paul Montariol, of the French Flying^ Corps. 

A complete glossary of practically all terms used in aviation. ha\'ing lists in botli 
French and Enghsh with equivalents in either language. 1 rice, net . . $1.00 

AVIATION CHART— LOCATION OF AIRPLANE POWER PLANT TROUBLEsf 
MADE EASY. By Major Victor W. Page, A.S., S.C.U.S.l^. 

A large chart outlining all parts of a typical airplane power plant, showing the points 
where trouble is apt to occur and suggesting remedies for the common defects. In- 
tended especially for aviators and aviation mechanics on school and field dutj. . 
Price .4 35 ceniajj 

BRAZING AND SOLDERING 



BRAZING AND SOLDERING. By James F. Hobart. 

The only book that shows you just how to handle any job of brazing or soldering thaft 
comes along; it tells you what mixture to use, how to make a furnace if you need on< . 
Full of valuable kinks. The fifth edition of this book has just been published, and t ) 
it much new matter and a large number of tested formulde for all kinds of solders atid 
fluxes have been added. Illustrated 35 cculi 

8 



CATALOGUE OF GOOD, PRACTICAL BOOKS 



. CHARTS 

A.VIATION CHART— LOCATION OF AIRPLANE POWER PLANT TROUBLES 
MADE EASY. By Major Victor W. Pagi^, A.S., S.C.U.S.R. 
A large chart outlining all parts of a typical airplane power plant, showing the points 

[ where trouble is apt to occur and suggesting remedies for the common defects. 

i Intended especially for aviators and aviation mechanics on school and field duty. 

^ Price 35 cents 

GASOLINE ENGINE TROUBLES MADE EASY— A CHART SHOWING SEC- 
TIONAL VIEW OF GASOLINE ENGINE. Compiled by Victor W. Page. 

It shows clearly all parts of a .typical four-cyhnder gasoline engine of the four-cycle 
type. It outlihes distinctly all parts liable to give trouble and also details the de- 
rangements apt to interfere with smooth engine operation. 

Valuable to students, motorists, mechanics, repairmen, garagemen, automobile sales- 
men, chauffeurs, motor-boat owners, motor-truck and tractor drivers, aviators, motor- 
cyclists, and all others Avho have to do with gasoline power plants. 
It simplifies location of all engine troubles, and while it will prove invaluable to the 
novice, it cao be used to advanta2;e by the more expert. It should be on the walls of 
every public and private garage,'automobile repair shop, club house or school. It can 
be carried in the automobKe or pocket with ease and will insure against loss of time 
when enc^ine trouble manifests itself. 

This sectional view of eneine is a complete review of all motor troubles. It is pre- 
pared by a practiccil motorist for all who motor. No details omitted. Size 25x38 
mches 35 cents 

wUBRICATION OF THE MOTOR CAR CHASSIS. 

This chart presents the plan view of a typical six-cylinder chassis of standard design 
and all parts are clearly indicated that demand oil, also the frequency with which they 
must be lubricated and the kind of oil to use. A practical chart for all interested in 
motor-car maintenance. Size 24x38 inches. Price 85 cents 

(Location of carburetion troubles made easy. 

This chart shows all parts of a typical pressure feed fuel supply system and givea 
causes of trouble, how to locate defects and means of remedying them. Size 24x38 
inches. Price . . .- 35 cents 

OCATION OF IGNITION SYSTEM TROUBLES MADE EASY. 

In this chart all parts of a typical double ignition system using batterj' and magneto 
current arc shown and suggestions are given for readily finding ignition troubles and 
eliminating them when found. Size 24x38 inches. Price 35 cents 

»OCATION OF COOLING AND LUBRICATION SYSTEM FAULTS. 

This composite "chart shows a typical automobile power plant using pump circulated 
water-cooUng system and the most popular lubrication method. Gives suggestions 
for curing all overlieating and loss of power faults due to faulty action of the oiling or 
cooling group. Size 24x38 inches. Price 35 cents 

LOCATION OF STARTING AND LIGHTING SYSTEM FAULTS. 

The most complete chart yet de^dsed, showing all parts of the modem automobile 
starting, lighting and ignition systems, gi\'ing instructions for systematic location of 
all faults in wiring, lamps, motor or generator, switches and all other units. Invaluable 
to motorists, chauffeurs and repairmen. Size 24x38 inches. Price . . 35 cents 

iOTORCYCLE TROUBLES MADE EASY— A CHART SHOWING SEC- 
TIONAL VIEW OF SINGLE-CYLINDER GASOLINE ENGINE. CompUed 
b}^ Victor W. Page. 

This chart simplifies location of all power-plant troubles, and will prove invaluable to 
all who have to do with the operation, repair or sale of motorcycles. No details 
omitted. Size 25x38 inches. Price 85 cents 



CATALOGUE OF GOOD, PRACTICAL BOOKS 

LOCATION OF FORD ENGINE TROUBLES MADE EASY. Compiled by 
Victor W. Page, M.E. 

This shows clear sectional views depicting all portions of the Ford power plant an( 
auxiUary groups. It outlines clearly all parts of the engine, fuel supply system 
ignition group and cooUng syitt6m, that are apt to give trouble, detaihng all derange- 
ments that are hable to make an engine lose power, start hard or worK irregularly. This 
chart is valuable to students, owners, and drivers a^ it simphties location of all engine 
faults. Of grv3at advantage as an instructor for the novice, it can be used equally well 
by the more expert as a work of reference and review. It can be carried in the tool- 
box or pocket with ease and will save its cost in labor ehminated the first time engine 
trouble manifests itself. Prepared with special reference to the averaere man's needs 
and is a practical revietv of all motor troubles because it is based on the actual ex- 
perience of an automobile engineer-mechanic vdth the mechanism the chart describes. 
It enables the non-technical owner or operator of a Ford car to locate engine de- 
rangements by systematic search, guided by easily'recognized symproms instead of by 
guesswork. It makes the average owner independent of the roadside repair shop 
when touring. Must be seen to be appreciated. Si^e 25x38 inches. Printed on heavy 
bond paper. Price 35 cents 

MODERN SUBMARINE C^ART — WITH 200 PARTS NUMBERED AhD 
NAMED. 

A cross-section view, showing clearly and distinctly all' the interior of a Submarine ol 
the latest type.^ You get more information from this chart, about the construction and 
operation of a Submarine, than in anv other way. No details omitted — everything 1 
is accurate and to scale. It is absolutely correct in every detail, havinii: been approved 
by Naval Engineers. All the machinery and devices fitted in a modem Submarine 
Boat are shown, and to make the engraving ma^o readily imderstooi.all the features 
are shown in operative form, with Officers and Men in the act of performing the duties 
assigned to them in service conditions. This CHART IS ilEALLY AN ENCYCLO-I 
PEDIA OF A SUBMARINE 25 cent 

BOX CAR CHART. 

A chart showing the anatomy of a box car, having every ptrt of the car numbered and 
its proper name given in a reference fist 25 cents 

GONDOLA CAR CHART. 

A chart showing the anatomy of a gondola car, having every part of the car numbered 
and its proper reference same given in a reference Ust 25 cents 

PASSENGER-CAR CHART. 

A chart showing the anatomy of a passenger-car, having every part of the car numbered 
and its proper name given in a reference fist 25 centi 

STEEL HOPPER BOTTOM COAL CAR. 

A chart showing the anatomy of a steel Hopper Bottom Coal Car, having ev^ry pariji] 
of the car numbered and its proper name given in a reference list 25 centi]" 

TRACTWE POWER CHART. 

A chart whereby you can find the tractive power or drawbar pull of any locomotive! 
without making a figiu-e. Shows what cylinders are equal, how driving wheels aTio 
steam pressure affect the power. What sized engine you need to exert a given drawbai 
pull or anything you desire in this Une 50 cents 



flORSE-POWER CHART 

Shows the horse-power of any stationary engine without calculation. No matter wba] 
the cyhnder diameter of stroke, the steam pressure of cut-off, the revolutions. 01 j 
whether condensing or non-condensing, it's all there. Easy to use. accurate, nu 
saves time and calculations. Especially useful to engineers and designers. 50 eci t; 

10 j| 







CATALOGUE OF GOOD, PRACTICAL BOOKS 



OILER ROOM CHART. By Geo. L. Fowler. 

A chart — size 14x28 inches— ^showing in isometric perspective the mechanisms be- 
longing in a modern boiler room. The various parts are shown broken or removed, 
so that the internal construction is fully illustrated. Each part is given a reference 
number, and these, with the corresponding name, are given in a glossary printed at 
the sides. This chart is really a dictionary of the boiicr room — the names of more than 
200 parts being given * 25 cents 

COKE 

OKE— MODERN COKING PRACTICE, INCLUDING ANALYSIS OF 
MATERIALS AND PRODUCTS. By J. E. CifRisTt)PHER and T. H. Byrom. 
This, the standard work on the subject, has just been re\^sed and is now issued in 
two voliftnes. ♦It is a practicsll work for those engaged in Coke manufacture and 
the recovery of By-products. Fully illustrated with folding plates. It has been 
the aim of the authors, in preparing this book, to produce one which shall be of use 
and benefit to those who are associated with, or interested in, the modern develop- 
ments of the industry. Among the chapters contained in Volume I are: Introduc- 

.,tion. Classification of Fuels. Impurities of Coals. Coal Washing. SampUng 
and Valuation of Coals, etc. Clilorific Power of fuels. History of Coke Manu- 
facture. Developments in Co^e Oven Design; Recent Types of Coke Ovens. 
Mechanical AppUances at Coke Ovens. Chemical and Physical Examination of 
Coke. Volume II covers By-products. Each volume is fully illustrated, with 
folding plates. Price, per volume , . . . $8.00 

COMPRESSED AIR 

OMPRESSED AIR IN ALL ITS APPLICATIONS. By Gardner D. Hiscox. 

This is the most complete book on the subject of Air that has ever been issued, and its 
thirty-five chapters include about every phase of the subject one can think of. It may 
be called an encyclopedia of compressed air. It is written by an expert, who. in its 
665 pages, has dealt with the subject in a comprehensive,manner, no phase of it being 
omitted. Includes the*physical prv2/perties of air from a vacuum to rts highest pressure, 
its thermodynamics, compression, transmission and uses as a motive power, in the 
Operation of Stationary and Portable Machinery, in Mining, Air Tools, Air Lifts. 
Pumping of Water, Acids, and Oils; the Air Blast for Cleaning and Painting, the 
Sand Blast and its Work, and the Numerous AppUances in which Compressed Air is 
a Most Convenfent and Economical Transmitter of Power for Mechanical Work, 
Railway Propulsion, Refrigeration, and the Various Ufx?s to which Compressed Air 
I has been apphed. Includes forty-ibur tables of the physical properties of air, its 
i compression, expansion, and volimies required for various kinds of work, and a Ust 
of patents on compressed air from 1875 to date. Over 500 illustrations, 5th Edition, 
revised and enlarged. Cloth bound. Price $6.00 

CONCRETE ^ 

jJST PUBLISHED— CONCRETE WORKERS' REFERENCE BOOKS. A 

I SERIES OF POPULAR HANDBOOKS FOR CONCRETE USERS. 

Prepared by A. A. Houghton - Each 60 cents 

The author, in preparing this Series, has not only treated on the usual types of construction ^ 
hut exDlains and illustrates molds and systems that are not patented, but which are equal 
in value and often superior to those restricted by patents. These molds are very easily and 
cheaply constructed and embody simnlicitij, rapidity of operation, and the most successful 

\ results in the molded concrete. Each of these Twelve books is fully illustrated, and the 

( subjects are exhaustively treated in plain English. 

JDNCRETE WALL FORMS. By A. A. Houghton. 

A new automatic wall clamp is illustrated with working drawings. Other types of 
wall forms, clamps, separators, etc., are also illustrated and explained. 
J (No. 1 of Series) 75 cents 

1 II 



CATALOGUE OF GOOD, PRACTICAL BOOKS 



CONCRETE FLOORS AND SIDEWALKS. By A. A. Houghton. 

The molds for molding squares, hexagonal and many other styles of mosaic floor ar. 
sidewalk blocks are fuUy illustrated and explained. (No. 2 of Series) . . 75 cent 

PRACTICAL CONCRETE SILO CONSTRUCTION. By A. A. Houghton. 

Complete working drawings and specifications are given for several styles of concre: 
silos, with illustrations of molds for monolithic and block silos. The tables, data, an . 
information presented in this book are of the utmost value^n planning and constructin \l 
all forms of concrete silos. (No. 3 of Series) 75 cent 

MOLDING CONCRETE CHIMNEYS, SLATE AND ROOF TILES. By A. J 

Houghton. 

The manufacture of a 1 types of concrete slate and roof tile is fully treated. Valuab 
data on all forms of reinforced concrete roofs are contained within its pages. TL 
construction of concrete chimneys by block and monolithic systems- is fully illustrate 
and described. A number of ornamental designs of chimney construction with mok 
are shown in this valuable treatise. (No. 4 of Series.) % . 75 cenl 

MOLDING AND CURING ORNAMENTAL CONCRETE. By A. A. Houghton 

The proper proportions of ccimont and aggregates for various finishes, also the methr 
of thoroughly mixing and placing in the molds, are fully treated. An exhausti^ 
treatise on this subject that every concrete worker will find of daily use and valu- 
(No. 5 of Series.) 75 cenf 

CONCRETE MONUMENTS, MAUSOLEUMS AND BURIAL VAULTS. B 
A. A. Houghton. 

The molding of concrete ng^onuments to imitate the most expensive cut stone is e: 
plained in this treatise, with working drawings of easily built molds. Cutting ii 
scriptions and designs are also fully treated. (No. 6 of Series.) ... 75 centi 

MOLDING CONCRETE BATHTUBS, AQUARIUMS AND NATATORIUMS 
By A. A. Houghton. 

Simple molds and instruction are given for molding many styles of concrete bathtul ^ 
swimming-pools, etc. These molds are easily^ built and permit rapid and successi 
work. (No. 7 of Series.) 75 ceni 

CONCRETE BRIDGES, CULVERTS AND SEWERS. By A. A. Houghto: 

A number of ornamental concrete bridges with illustrations of molds are given, 
collapsible center or core for bridges, culverts and sewers is fully illustrated with d 
tailed instructions for bU'ilding. (No. 8 of Series.) 75 cen 

CONSTRUCTING CONCRETE PORCHES. By A. A. Houghton. 

A number of designs with working drawings of molds are fully explained so any or 
can easily construct different styles of ornamental concrete porches without the pu 
chase of expensive molds.. (No. 9 of Series.) 75 cen I 

MOLDING CONCRETE FLOWER-POTS, BOXES, JARDINIERES, ETC 
By A. A. Houghton. 

The molds for producing many original designs of flower-pots, urns, flower-boxi^ 
jardinieres, etc., are fully illustrated and explained, so the worker can easily constrm 
and operate same. (No. 10 of Series.) 75 cen I 

MOLDING CONCRETE FOUNTAINS AND LAWN ORNAMENTS. By ! 
A. Houghton. 

The molding of a number of designs of lawn seats, curbing, hitching posts, pergolas, s . 
dials and other forms of ornamental concrete for the ornamentation of lawns and ga 
dens, is fully illustrated and described. (No. 11 of Series) 75 cec 

CONCRETE FROM SAND MOLDS. By A. A. Houghton. 

A Practical Work treating on a process which has heretofore been held as a trade seen 
by the few who possessed it, and which will successfully mold every and any class • 
ornamental concrete work. The process of molding concrete with sand molds is « 

12 



^l 



CATALOGUE OF GOOD, PRACTICAL BOOKS 



the utmost practical value, i)o&.s(^ssing the manifold advantages of a low cost of molds 
I the ease and rapidity of operation, perfect details to ail ornamental designs density 
and increased strength of the concrete, perfect curing of the work without attention 
and the easy removal of the molds regardless of any undercutting the design may have 
192 pages. Fully illustrated. Price • r $2.00 

RNAMENTAL CONCRETE WITHOUT MOLDS. By A. A. Houghton. 

The process for making ornamental concrete without molds has long been held as a 

secret, and now, for the first time, this process is given to the pubUc. The book 

reveals the secret and is the only book published whuch explains a simple, practical 

method whereby tlie concrete worker is enabled, by^employing wood and metal tem- 

I plates of different designs, to mold or model in concrete any Cornice. Archivolt, 

] Column, Pedestal, Base Cap, Urn or Pier in a monolithic form — right upon the job 

, These may be aiolded in units vr blocks, and then built up to suit the specifications 

( demanded. This work is fully illustrated, with detailed engravings. Price . $2.00 

DNCRETE FOR THE FARM AND IN THE SHOP. By H. Colin 
Campbell, C.E,, E.M. 

[. "Concrete for the Farm and in the'Shop" is a new boolc from cover to cover, illustrat- 
; irjg and describing in plain, simple language many of the numerous applications of 
J concrete within the range of the home worker. Among the subjects treated are: 

Principles of reinforcing ; methods of protecting concrete so as to insure proper harden- 
r Ing; home-made mixers; mixing by hand and machine; form cons; ruction, described 
and illustrated by drawings and photographs; construction of concrete walls and 
fences; concrete fence posts; concrete gate posts; comer posts; clothes line posts- 
t grape arbor posts; tanks; trouglis; cisterns; hog waliows: feeding floors and barn- 
yard pavements; foundations; welF curbs and platforms; indoor floors ; sidewalks* steps- 
D concrete hotbeds and cold frames; concrete slab roofs; walls for buildings- reijairing 
i leaks in tanks and cisterns; and all topics associated with these subjects as bearing 
I upon securmg the best results from concrete are dwelt upon at sufficient length in plain 
every-day English so' that the inexperienced person desiring to undertake a piece of 
I concrete construction can, by following the directions set forth in this book secure 100 
I per cent success every time. A number of convenient and uractical tables for estimating 
!" quantities, and some practical exa'mples, are also given. (5x7). 149 pages 51 il- 
^ lustrations. Price ° '$i.00 

)PULAR HANDBOOK FOR CEMENT AND CONCRETE USERS. By 

Myron H. Lewis. 

a This is a concise treatise of the princyple^ and methods employed in the manufacture 
and use of cement m all classes of modern works. The author has brought together 
m this work all the salient matter of interast to the user of concrete and its many 
1 diversified products. The matter is presented in logical and systematic order, clearly 
- written, fully Ulustrated and free from involved mathematics. Evervthing of value to 
the concrete iiser is given, including kinds of cement employed in construction, concrete 
^architecture, mspection and testing, waterproofing, coloring and painting, rules, tables 
J working and cost data. The book comprises thirty-three chapters, as follows: 
Introductory. Kinds of Cements and How They are Made. Properties. Testing 
and Requirements of Hydraulic Cement. Concrete and its Properties. Sand Broken 
i1 Stone and Grave for Concrete. How to Proportion the Materials. How to Mix 
i; and Place Concrete. Forms of Concrete Construction. The Architectural and Artistic 
n Possibilities of .Concrete. Concrete Residences. Mortars. Plasters and Stucco, and 
How to Use them. The Artistic Treatment of Concrete Surfaces. Concrete Building 
(Blocks. The Making of Ornamental Concrete. Concrete Pipes, Fences. Posts, etc. 
Essential Features and Advantages of Reenforced Concrete. How to Design Reen- 
I forced Concrete Beams. Slabs and Columns. Explanations of the Methods and 
Principles in Designing Reenforced Concrete Beams and Slabs. Svstems ol Reen- 
forcement Employed. Reenforced Concrete in Factorv and General Building Con- 
struction. Concrete in Foimdation Work. Concrete Retaining Walls, Abutments 
.and Bulkheads. Concrete Arches and Arch Bridges. Concrete Beam and Girder 
jBndges. Concrete in Sewerage and Drainage Works. Concrete Tanks. Dams and 
1 Reservoirs. Concrete Sidewalks. Curbs and Pavements. Concrete in Railroad Con- 
structions. The Utility of Concrete on the Farm. The Waterproofing of Concrete 
Structure. Grout of Liquid Concrete and Its Use. Inspection of Concrete Work. Cost 
of Concrete Work. Some of the special features of the book are: 1. The Attention 
jPaid to the Artistic and Architectural Side of Concrete Work. 2. The Authoritative 

i 13 



CATALOGUE OF GOOD, PRACTICAL BOOKS 



Treatment of the Problem of Waterproofing Concrete. 3. An Excellent Summary c 
the Rules to be Followed in Concrete Construction. 4. The Valuable Cost Data an 
Useful Tables given. A valuable Addition to the Library of Every Cement ar 
CJoncrete User. Price . $3.0 

WHAT IS SAID OF ^HIS BOOK: 
•'The field of Concrete Construction is well covered and the matter contained is we 
within the understanding of any person." — Engineering-Contracting. 
"Should be on the bookshelves of every contractor, engineer, and architect in th 

Isind.''— National Builder. 

WATERPROOFING CONCRETE. By Myron H. Lewis. 

Modem Methods of Waterproofine Concrete an^ Other Structures. A condense ir 
statement of the Principles, Rules, and Precautions to be Observed in Waterproofii p 
and Dampprooflng Structures and Structural ^Materials. Paper binding. Illustrate* 
Price ~ 75 cent 

DICTIONARIES 

STANDARD ELECTRICAL DICTIONARY. By T". O'Conor Sloans. 

An indispensal^e work to all interested in electrical science. Suitable aUke for th 
student and professional. A practical handbook of reference cnntaining dertnitions 
about 5000 distinct words, terms and phrases. The definitions are terse and conci- 
and include every term use<^ in electrical science. Recently issued. An entirely in 
edition. Should be in the possession of all who desire to keep abreast with the progrc 
of this branch of science. Complete, concise and convenient/ Nearly 800 pages. Neari 
500 illustrations. 1920 Revised and Enlarged Edition. Price $5.0 

AVIATION TERMS— ENGLISH-FRENCH; FRENCH-ENGLISH. By Maj( 
Victor W. Page, A.?., S.C.U.S.R., and Lieut. Paul Montariol of t: 
French Flying Corps. 

A complete glossary of practically all terms used in aviation, having lists in bo 
French and Enghsh with equivalents in either language. Include all words 
common use. A complete, well illustrated volume intended to facilitate convert 
tion between EngUsh-speaking and French a^^ators. The lists are confined to essti 
tials, and special folding plates iive included to show all important airplane pari 
The Usts are divided into foiu* sections: 1. t lying Field Terms. 2. The Airplaii 
3. The Engine. 4. Tools and Shop Terms. Should be in every aviator's an 
mechanic's kit. Price $1.0 

PrES— METAL WORK 

DIES: THEIR CONSTRUCTION AND USE FOR THE MODERN WORKIN' 
OF SHEET METALS. ,By J. V. Woodworth. 

A most useful book, and one which should be in the hands of all engaged in the pre, 
working of metals; treatins: on the Desisrning, Constructing, and Use of Tools, Fixtui«lT 
and Devices, toajether with the manner in which they should be used in the Pov^ • 
Press, for the cheap and rapid production of the great variety of sheet-metal artic 
now in use. It is designed as a guide to the nroduction of sheet-metal parts at I 
minimum of cost with the jnaximum of output. The hardening and tempering 
Press tools and the classes of work which may be produced to the l>est advantage 
the use of dies in the power press are fully treated. Its 505 illustrations show di • 
press fixtures and sheet-metal workins: devices, the descriptions of which are so clear a 
pract>ical that all metal- worldng mechanics will be able to understand how to desic 
construct and use them. Many of the dies and press fixtures treated were eitl ■ 
constructed by the author or under his supervision. Others were built by skir 
mechanics and are in use in large sheet-metal estabhshments and machine sho • 
6th Edition. Price $3.^ 



14 



CATALOGUE OF GOOD, PRACTICAL BOOKS 



[INCHES, DIES AND TOO;.S FOR MANUFACTURING IN PRESSES. By 

J. V. WOO'DWORTH. 

This work is a companion volume to the author's elementary work entitled "Dies Their 
Construction and Use.' It does not go into the dp/?.ils of die-making to the extent of 
the author s pre\aous book, but gives ^ comprehensive re\ievv of the tield of operations 
carried on by presses. A large part of the information aivea has been drawn from the 
author s personal experience. K might well be termed an Encvclopedia of Die-Making 
Punch-Malaiig, Die-Sinking, Sheet-Aietal Working, and Making of Special Tools, Sub- 
presses, Devices and Mechanical Combinations for Punching, Cutting, Bending Form- 
ing. Piercing, Drawing, Compressing and Assembling Sheet-Metal Parts, and also Arti- 
cles ol other Materials in Machine Tools. 2d Edition. Price $4.50 

ROP FORGING, DIE-SINKING AND MACHINE -FORMING OF STEEL. 

: By J. V. WOODWORTH. 

i ^ 

This is a practical treatise on ZVIodern Shop Practice, Processes, ^Methods, Machine 
Tools and Details /r eating on the Hot and Cold Machine-Forming of Steel and Iron 
into Finished j-'hapes; together with Tools, Dies, and Machinery involved in the 
manufacture of Duplicate Forgings and Interchangeable Hot and Cold Pressed Parts 
from Bar and Sheet Metal. Thir- book fills a demand of long standing for information 
regarding drop -forgings, d*o-sinking and ma hine-formin-c of steel and the shoD 
practice involved, as .t actually exists in the modern drop-forging shop. The processes 

J of die-sinkin^ and force-making, which are thoroughly described ancA illustrated in this 

, admirable work, are, rarely to be found explained in such a clear and concise manner 
as IS here set forth. Ihe process of die-sin[dng relates to the engraving or sinkin'' of 

, the female or lower dies, such as are us (3d for drop- forgings, hot and cold machine 

, forging swedging and the press forking of metals. Thf^ process of force-makins 
relates to the engravin,T or raising of the male or upper dies used in producing' the 

)Uower dies for the press-forming and machine-forging of duphcate parts of metal. 
In addition to the ar,ts above mentioned the book contains exphcit information re- 

,igarding the dr9p -forging and hardening plants, designs. c3hditions, equipment, drop 
hammers, forging^ machines, etc.. machine forging, hvclraulic forgin-. autogenous 

Tf^^o^^H^-^ !^^^ practi^ce. The b^ok contains eleven ch-ipters. and tlie information 
contained in these chapters is just ^vhat will prove most valuable to the forged-metal 

To/.,3.V- 1 operations described in the work are thoroughly illustrated bv^means of 
perspective half:t9nes and outline sketches of the machmery employed. 300 dialled 
Illustrations. Price. ^ a»o piz-v 



DRAWING— SKETCHING PAPER 

(ACTICAL PERSPECTIVE. By Eichards and Collin 

I 

Shows just how to make all kinds of mechanical drawings in the onlv nractical npr- 
l^efoh of H^.'17S- '^ll^^' everything plain so that any mechli^c Lf uStand 
^thnnf rnntn^nl'^^^^ ^^^^' i ^^"i^^ ^'^^ ^^*^^ drawing room, and mistakes in the 

^snops. Contains practical examples of various classes of work. 4th Edition. 75 cents 

Wr perspective self-taught. By Herman T. C. Kraus. 

Jn^fnrpHnor'J^H ^^^ ^^^^^^ i^^^i^ practicc of linear perspective, as used m architectural, 
engineering and raechamcal dra^vings. Persons taking up the studv of the suht^ 
by themselves will be able, by the use of the ins tructFon given to reaSlv grl^n thi 
merit''o>Th^P^b^;n?'^^^^^"HP'.l"'^"1 ^^^^^e good perspectU^e draftsmen The^^^ng^ 
Kt. nn th^^.^'JX.i'-f'''''^^ ^^^ P^^^^ K""'^ ^^^ left-hand, while the descriptive text 
Kffl^L?P the, opposite page, so as to be readily referred to. The drawings are on 
in^^?c^T^I.iffl^^?^^^ clearl/and are plainly figured. There 5 

iSiderstindin^^ ^^^^''VZ?''''^ ^'Z'^'^^ information necesiar/for the thorough 

^etoar^2S'R"evFsl^^^^^^^^ ^f --^^^ ^^^J '^^ ^.-^ '^^ %'§-of 

f 15 



CATALOGUE OF GOOD, PRACTICAL BOOKS 



SELF-TAUGHT MECHANICAL DRAWING AND ELEMENTARY MACHINI 
DESIGN. By F. L. Sylvester, ALE., Draftsman, with additions by Erii 
Oberg, associate editor of "Machinery.'^ 

This is a practical treatise on Mechanical Drawing and ^Machine Design, comprising! 
the first principles of geometric and mecbanical drav,ang, workshop mathematics 
mechanics, strength of materials and the calculations and design of machine details 
The author's aim has been to adapt this treatise to the requirements of the practica 
mechanic and young draftsman and to present the matter in as clear and concise ; 
manner as possible. To meet the demands of this class of students, practicaUy all tl 
important elements of machine design have been dealt with, and in addition algebra 
formulas have been explained, and the element^ of trigonometry treated in the manri 
best suited to the needs' of the practical man. The book is divided into 20 chaptei 
and in arranging the material, mechanical drawinu, pure and simple, has been taki 
up first, as a thorough understanding of the principles of representimr objects facilitat 
the further study of mechanical subjects. This is followed by the mathematics necf 
sary for the solution of the problems in machine design which are presented later, ai 
a practical introduction to theoretical mechanics atul the strength of materials. Tl 
various elements entering into machine design, such as cams, gears, sprocket-wheel 
cone pulleys, bolts, screws, couplings, clutches, shafting and- fly-wheels, have be< 
treated in such a way as to. make possible the use of the work as a text-book for . 
continuous course of study. It is easily comprehended and assimilated even h: 
students of Umited previous training. 330 pages, 1^15 engravings. Price . . $2.5 ( 

A NEW SKETCHING PAPER. 

A new specially ruled paper to enable you to make sketches or drawings in isometr 
perspective without any figyiring or fussing. It is being used for shop details as w< 
as for assembly drawings, as it makes one sketch'do the work of three, and no workma 
can help seeing just what is wanted. Pads of 40 sheets, 6x9 inches, 25 cents. Pa<-i 
of 40 sheets, 9x12 inches, 50 cents; 40 sheets, 12x18, Price $1.0< 

, ELECTRICITY 

/ARITHMETIC OF ELECTRICITY. By Prof. T. O'Conor Sloane. I 

A practical treatise on electrical calculations of all kinds reduced to a series of rules, t 
of the simplest forms, and involving only ordinary arithmetic; each rule illustrate 
by one or more practical problems, with detailed solution of each one. This book i 
classed among the most useful works published on the science of electricity, coverin 
as it does the mathematics of electricity in a manner that will attract the attentio 
of those who are not familiar with algebraical formulas. 20th Edition. 160 pagcsll 
Price * $1.5«[ 

COMMUTATOR CONSTRUCTION. By Wm. Baxter, Jr.' \ 

The business end of any dynamo or motor of the direct current type is the commutatoij 
This liook goes into the designing, building, and maintenance of commutators, sho^ 
how to locate troubles and how to remedy them; everj'one who fusses with dynamc>l 
needs this. 4th Edition ., 35 cent 

DYNAMO BUILDING FOR AMATEURS, OR HOW TO CONSTRUCT 
FIFTY- WATT DYNAMO. By Arthur J. Weed, :Member of N. Y. Electric . 

Society. I 

A practical treatise showino'In detail the construction of a small dyrvamo or motor, fit 
entire machine work of which can be done on a small foot lathe. Dimensioned worki i 
drawings are given for each piece of machine work, and each operation is cleail 
described. This machine, when used as a dynamo, has an output of fifty watts: wL 
used as a motor it will drive a small drill press or lathe. It can be used to drive 
sewing machine on any o^nQ. all ord!narv work. The book is illustrated with mt i 
than sixty original engravings showing the actual construction of the different par 
4mong the contents are chapters on: 1. Fifty- Watt Dynamo. 2. Side Bean i 

i6 i 



CATALOGUE OF GOOD, PRACTICAL BOOKS 



Rods. 3. Field Punching. j,4. Bearings. 5. Commutator. 6. Pulley. 7. Brush 
Holders. 8-. Connection Board. 9. Armature Shaft. 10. Armature. 11. Armature 
Winding. 12. Field Winding. 13. Connecting and Starting. Price, cloth, $1.00 

LECTRIC WIRING, DIAGRAMS AND SWITCHBOARDS. By Newton 
Harrison. 

A thoroughlj^ practical treatise covering the subject of Electric Wiring in ail its branches 
including explanations and diagrams which are thoroughly 'jxplicit and greatly simplify 
the subject. Practical, every-day problems in wiring are presented and the method 



various appUcations. The simple circuit is developed with the position of mains, 
feeders aud br^;iches; their treatment as a part of a wiring plan and their employ- 
ment in house wiring clearly illustrated. Some simple facts about testing are included 
in connection with the wiring. Molding and conduit work are given careful considera- 
tion; and switchboards are sy^ematicaUy treated, built up and illustrated, showing 
the purpose they serve, for. connection with the circuits, and to shunt and compound 
wound machines. ,The simple principles of switchboard construction, the develop- 
ment of the switchboard, the connections of the various instruments, including the 
lightning arrester, are also plainly set forth. 

Alternating current wiring fe treated, with explanations of the power factor, conditions 
calling for various sizes of wire, and a simple way of obtaining the sizes for single-phase, 
two-phase and three-phase circuits. This is the only complete werk issued showing 
and telling you what you should know about direct and alternating current wiring. It 
is a ready reference.* The work is free from advanced technicalities and mathematics, 
arithmetic being used throughout. It is in every respect a handy, well- written, 
instructive, Comprehensive volume on wiring for the wireman. foreman, contractor, 
or electrician. 272 pagers; 105 illustrations. Price $2.50 

:ECTRIC toy making, dynamo building, and ELECTRIC MOTOR 
CONSTRUCTION. By Prof. T. O'Conor Sloane. 

This work treats of the aiaking at hpme of electrical toys, /electrical apparatus, motors, 
dynamos and instruments in general, and is designed to bring within the reach of 
yoimg and old the manufacture of genuine and useful electrical appliances. The work 
is especially designed for amateurs and young folks. 

Thousands of our young people are daily experimenting, and busily engaged in making 
electrical toys and> apparatus of various kinds. The present work is just what is want- 
ed to give the much needed information in a plain, practiap.1 manner, with illustrations 
I to ma^e easy the carrying out of the ^ork. 20th Edition. Price . . . . $1.50 

[.ECTRICIANS' HANDY BOOK. By Prof. T. O'CoxNOr Sloane. 

[ This work is intended for the practical electrician who has to make things go. The 
1 entire field of electricity is covered within its oages. Among some of the subjects treated 
are: The Theory of the Electric Current and Circuit, Electro-Chemistry, Primary 
Batteries. Storage Batteries, Generation and Utihzation of Electric Powers, Alter- 
' nating Current, Armature Winding. Dynamos and [Motors. Motor Generators, 
I Operation of the Central Station Switchboards, Safety Appliances, Distribution 
I of Electric Light and Power, Street IMains, Transformers, Arc and Incandescent 
I Lighting, Electric ;^Ieasurements, Photometry, Electric Railways, Telephony, Bell- 
I Wiring, ElectriC-Plating, Electric Heating, Wireless Telegraphy, etc. It contains no 
I useless theory; everything is to the point. It teaches you just what you want to 
I know about electricity. It is the standard work published on the subject. Forty- 
I six chapters, 600 engravings. 1920 Revised and Enlarged Edition. Price . $4.00 

'.ECTRICITY gIMPLI¥lED. By Prof. T. O'Conor Sloane. 

I The object of "Electncitv Simplified" is to make the subject as plain as possible and 

I to show what, the modern conception of electricity is; to show how two plates of 

I different metal, immersed in acid, can send a message aroimd the globe; to expiam 

I how a bundle of copper wire rotated by a steam engine can be the agent m lighting 

our streets, to tell what the volt, ohm and ampere are. and what high and low tension 

mean: and to answer the questions that perpetually arise in the mmd m this age <rf 

electricity. 13th Edition. 172 pages. Illustrated. Price $1.00 

17 



CATALOGUE OF GOOD, PRACTICAL BOOKS 



EXPERIMENTAL WIRELESS STATIONS. By »?. E. Edelman., 

The theory design, construction and operation is fuUy treated mcluding Wirel^? 
Telepbonyf Vacuum Tube, and quenched spark ^yf ^"^f _The new en ar^d 1920 
pHition is iust issued and is strictlv up to date, correct and complete. Tins lx)Oti teii^ 
In^tV^lVe^n^a^rsitnsto n^*only hear aU telephoned and telegraphed radio mess^ 
aSS 'buTS^o how to maL ^^^^ that works for transm,s n over r^- 

Ronablv Ion- distances. Then there is a host of r new mformation mcluded. The 
first and onlvbo^^^^^ you all the recent important racho imprpvements, some 

S which have never before been pubhshed. This volume ant ici^p a tes every neod of 
the reader who wants the gist of the art, its prmciples, simphfled calculations, appara^ 
frit HlmSision^ and understandable directions for efficient operation. 
V^um tSSf ci^cit^ rmpU long-distance sets; loop coil and under^ound 

rfSSVers tables of wave-lengths, capacity, inductance; such are a few of the sub- 
j^^fprl^entedln detail that%atisfies. It is independent and one of the few that 

Si^ld^by'^fS^eTosYinXctors for its clear accuracy, preferred by leading amateurs 
^r ited^eZdable d^^^^^ new experimental Wireless Stations is sure to be most 

satistcto^i^^^^^^ 24chlpters. 167 ^illustrations. Pnce . . ^3.00 

HOUSE WIRING. By Thomas W. Poppe. • 

Th^^ work describes and illilstrates the actual installation of Electric Light Wiring 

SvsteS The Fk^xible SteS Conduit System, ^he Ridig Conduit Aystem. A diges^ 
^f^?hP l^ational Boar^^^ of Fire Underwrkers' rules relaring.to metallic vvunng systerasi 
VarLuf Sh n- arr^^^^ and dia^^ramined. The.easiost method o 

w n- tho ThreS- a^^^^^^ circuits explained. The grounding of all metaUi. 

wfiinl systems a^^ reason for doing so shown and ^^l'^^^^^^-.,J^^^^^ 

fihP rnPtal narts of lamp fixtures and the reason for the same desrnbed and illustrate i 
125 plg^.'^^nd iiS^ and enlarged. Fully iUustrated. Flexible clot^. 

Price ' 

WHAT IS SAID OF THIS BOOK: 
"The information given is exact and exhaustive without being too technical or over 
laden with details." — Druggiats' Circular. 
HOW TO BECOME A SUCCESSFUL ELECTRICIAN. By Prof. T. O'Conoi 

SLOANB. , , , J xr.. 1. ' 

Every yotmg man who wishes to become a successful electrician should ^^.^^this boo|i 
It teh^in^mple language the surest and easiest way to become a successful electrician 
The studilftS be fe^^ methods of work, field of operation and the requirement 

of the succeSful eS are pointed out and fully explained. Ev<?ry ypung en 

gUer wuftod'L's an excellent stepping stone to S,^^" ^jl^^^Sf^^^^^^^ 
which he must master before success can be attained, ^^^ny yoimg me^n b^^^^ 
couraged at the very outstart by attempting to read and study books that are la 
H^^o1?H thPir romnrehension. This book serves as the connecting link between tin 
mdfml^ toughT to thf ^^^ schools and the real study of electricity. It is mte i 
StinTfrom elver to cov^. Eighteenth Revised Edition, just issued. 205 page. 

Illustrated. Price • , . . . ^p . 

STANDARD ELECTRICAL DICTIONARY. By T. O'Conor Sloane. 

An indisDensable work to all interested in electrical science. Suitable alike for th 
^Sd?nt^ profersional. A practical handbook of reference contaimng clefinitior: 
of about 5 000 distinct words, terms and phrases. The definitions are terse an 
conoLse and include every term used in electrical science. R^ently issued. An ci , 
t?re?v ne^edftion ShoiJd be in the possession of all who desire to keep abreast wit 
the proles of this branch of science In its arrangement. and typography the bo 3 [, 
is verv^^venient. The word or term defined is printed in black-faced type whic 
rea^U^ caSSS the eye. while the body of the page is in smaller but distinct type. J 
rtPfinUionTare w^^^ -and so as to be understood by the non-teclimcal reade 

ThpLenerafDlZL s^ to give an exact, concise definition, and then amp if 

and expl^ iS a more'Top^^^^ Synonyms are also given, and references to othej 

l8 



CATALOGUE OF GOOD, PRACTICAL BOOKS 

words and phrases are made, A very complete and accurate index of fifty pages is 
at the end^of the vokirae; and as this index contains all synonyms, ar;d as all phrases 
are indexed in every reasonable combination of words, reference to the proper place 
in the body of the book is readily made. It is difficult to decide how far a book of 
this character is to keep the dictionary form, and to what extent it may assume the 
encyclopedia form. For some purposes, concise, eraeily worded definitions are needed ; 
for other purposes, more extended descriptions are required. This book seeks to satisfy 
botji demands, and does it with considerable success. Complete, concise and con- 
venient. 800 pages. Nearly 500 illustrations. 1920 Revised and Enlarged Edition- 
Price . . ^ $5.00 

IWITCHBOARDS. By William Baxteh, Jr. 

This book appeals to every engineer and electrician*who wants to know the practical 
side of things. It takes up all sorts and conditions of dynamos, connections and 
circuits, ^nd sl^ows by diagrant and illustration just how the switchboard should be 
connected. Includes direct and alternating current boards, also those for arc lighting, 
incandescent and power circuits. Special treatment on high voltage boards for power 
transmission. 2d Edition. 1^0 pages. Illiistrated. Price $2.00 

'ELEPHONE CONSTRUCTION, INSTALLATION, WIRING, OPERATION 
AND MAIIfTENANCE. By W. H. Radclifi^ and H. C. Gushing. 

This book is intended for the amatetir, the wireraan, or the engineer who desires to 

I establish a means of telephonic communication between the rooms of his home, office, 
or shop. It deals only with such things as may be of use to him rather than with 
theories. 

Gives the principles' of construction and operation of both the Bell and Independent 
instruments; approved methods of instaUing and wiring them; the means of protecting 
them from Kghtning and abnormal currents; their connection together for operation 
as series or bridging stations ; and rules for their inspection and maintenance. Line 

' wiring and the wiring and operation of special telephone systems are also treated. 

1 Intricate mathematics are avoided, and all apparatus, circuits and systems are thor- 
oughly described. The appendix contains definitions of units and terms used in the 
text. Selected wiring tables, which are very helpful, are also included. Among the 
subjects treated are Construction, Operation, and InstaKation of Telephone Instru- 

' ments; Inspection ancf Maintenance of Telephone Instruments; Telephone Line 
Wiring; Testing Telephone Line Wires and Cables; Wiring and Operation of Special 
Telephone Systems, etc. 2nd Edition, revised and enlarged. 223 pages. 154 

1 illustrations . . . ^ $1.50 

TIRELESS TELEGRAPHY AND TELEPHONY SIMPLY EXPLAINED, By 
Alfred P. Morgan. 

; This is midoubtedly one of the most complete and comprehensible treatises on the 
1 subject ever pubUshed,and a close study of its pages will enable one to master all the 
1 details of the wireless transmission of messages. The author has filled a long-felt 
( want and has succeeded in furnishing a lucid, comprehensible explanation in simple 
' language of the theory and practice of wireless telegrap'^iy and telephony. 

Among the contents are: Introductory; Wireless Transmission and Reception — The 
I Aerial System, Earth Connections — The Transmitting Apparatus, Spark Coils and 
Transformers, Condensers, Hehxes, Spark Gaps, Anchor Gaps, Aerial Switches — The 
Recei^dng Apparatus, Detectors, etc. — Tuning r.nd CoupUng, Tuning Coils, Loose 
\ Couplers, Variable Condensers, Directive Wave Systems — Miscellaneous Apparatus, 
Telephone Receivers, Range of Stations, Static Interierence — Wireless Telephones, 
Sound and Sound Waves, The Vocal Cords and Ear — ^Wireless Telephone, How Sounds 
Are Changed into Electric Waves — ^Wireless Telephones, The Apparatus — Summary. 
154 pages. 156 engravings. Price $1.50 

WHAT IS SAID OF THIS BOOK: 
"This book should be in both the home and school library." — The Youths* Instructor, 

TRING A HOUSE. By Herbert Pratt. 

Shows a house already built: t^Us just how to start about wiring it; where k> begin; 
what wire to use; how to run it according to Insurance ^Rules; in fact, just the informa- 
tion you need. Directions apply equally to a shop. Fourth edition . . 86 cents 

19 



CATALOGUE OF GOOD, PRACTICAL BOOKS 



RADIO TIME SIGNAL RECEIVER. By Austin^C. Lescarboura. 

This new book "A Radio Time Signal Receiver," tells you how to build a simplej 
outfit designed expressly for the beginner. You can build the outfits in your ow^i 
wor]^hop Ind instaU them for jewelers either on a one-payment or a rental basi.^ 
The apparatus is of such simple design that it may be made by the average amateu 
mecha^c possessing a few ormnary tools. 4'2 pages. Paper. Price . . 35 cent. 

CONSTRUCTION OF A TRANSATLANTIC ^V^/lRELESS RECEIVING SET. 
By L. G. Pacent and T. S. Curtis. 

A work for the Radio student who desires to p onstruct and operate apparatus thr 
wiU permit of the reception Qf messages from the large stations m Europe with a 
aerial of amateur proportions. 36 pages. 23 iUustrations. cloth. Price . 35 cent. 

ELECTRIC BELLS. By M. B. Sleeper. 

A complete treatise for the practical worker in ,1nstallmg, operating and testiiig 
beU circuits, burglar alarms, thermostats, and otiier apparatus used with electric 
bells Both the electrician and the experimenter will find in this book new materia 
which is essential in then- work. Tools, bells, batteries, umisual circmts, burgku 
alarms annunciators, systems, thermostats, circmt breakers, time alarms, and othei 
IppSus u^edln are described fron the standpoints of their apphca- 
tSnV construction, and repair. The detailed instructipns for building the apparatus 
wUl appeal to the experimenter particularly. The practical worker wiU find th. 
chapter^ on Wiring Calculation of Wire Sizes and Magnet Windings, Upkeep o 
SyXms and the Location of Faults of the greatest value m theu- work. 124 pag(. 
FuUy illustrated. Price : . . . 75 cent 

EXPERIMENTAL HIGH 'FREQUENCY APPARATUS — HOW TO MAKI 
AND USE IT. By Thomas Stanley Curtis. 

This book tells you how to build simple high frequency coils for experimental purpof 
in the home, school laboratory, or on the small lecture platform.^ Tlie book is real 
a supplement to the same author's " High Frequency Apparatus. The experiment 
side only is covered in this volume, wliich is ^intended for those who want to bui 
small coils givmg up to an eighteen-inch spark. The l»ook contains valuable J 
formation for the physics or the manual traimng teacher who is on the lookout f 
interesting projects for his boys to build or experiment with. The apparatus 
simple, cheap and perfectly safe, and with it some tmly ?t^y ^Img expenments may ^ 
performed. Among the contents are: Induction Coil Outfits Operated on Batte^ 
tfurrent Kicking CoU Apparatus. One-Half Kilowatt Translormer Outfit. Par 
and Materials, etc., etc. • 69 pages. lUustratcd. Price 50 cen 

HIGH FREQUENCY APPARATUS, ITS CONSTRUCTION AND PRACTICE 
APPLICATION. By Thomas Stanley Curtis 

The most comprehensive and thorough work on this interesting subject ever produce 
The book is essentially practical in its treatment and it constitutes an accurate reco 
of the researches of its author over a period of several years during winch time dozt. 
of coils were built and experimented with- The work has been divided into six ba: 
Darts The first two chapters tell the unmitiated reader what the high frequenO 
current is, what it is used for, and how it is produced. The second section. comprisiEi 
four chapters, describes ii* detail the prmciples of the transfi^irmer, condenser. sp;-E* 
ean and oscillation transformer, and covers the main pomts m Wie design and « 
Itruction of these devices as apphed to the work in hand. The third section .> : 
the construction of small high frequency outfits designed for experimental work in .i 
home laboratory or in the classroom. The fourth section is devoted to elect r^ 
therapeutic and X-Ray apparatus. The fifth describes apparatus for the cultivatij 
of plants and vegetables. The sixth section is devoted to a comprehensive discussij 
of apparatus of large size- for use upon the stage in spectacular productions xi 
closing chapter, giving the current prices of the rarts and materials required for JJ 
construction of the apparatus described, is included with a view to expediting « 
purchase of the necessary goods. The Second Edition includes much new mati 
along the line of home-made therapeutic outfits for physicians use. The matter « 
electro plant culture has al.so been elaborated upon. Second Revised and -Enlar^ 
Edition. 248 pages. 1920. Fully iUustrated. Price $o.H 

20 , 



CATALOGUE OF GOOD, PRACTICAL BOOKS 

JTORAGE BATTERIES SIMPLIFIED. By Victor W. Page, M.S.A.E. 

A complete treatise on storage battery operating principles, repairs and applicationa. 
The greatly increasing application of storage batteries in modem engineering and 
mechanical work has created a demand for a b^ok that will consider this subject 
completely and exclusively. This i^ the most thorough and authoritative treatise 
ever published on this subject. It is written in easily imderstandable, non technical 
language so that any one may grasp the basic principles of storage battery action as 
well as their practical indastrial apphcations. All electric and gasoline automobiles 
use storage batteries. Every automobile repairman, dealer or salesman should have a 
good knowledge of maintenance and rej^air of these important elements of the motor 
car mechanism. This book not otily tells how to charge, care for and rebuild storage 
batteries but also outlines all the industrial uses. « LeaiRi how they run street cars, 
locomotives and factory trucks. Get an understanding of the important functions they 
perform in submarine boats, isolated lighting plants, railway switch and signal systems, 
marine apphcations. etc. This book tells how they are used in central station standby 
service, for starting automobile motors and in ignition systems. Every practical use 
of the modern storage battery is outhned in this treatise. 

Chapters contained are: Chapter 1 — Storage Battery Development — Types of Storage 
Batteries — Lead J^late Types — The Edison Cell. Chapter 2 — Storage Battery 
Construction — Plates and Grids — Plante.riates — Faure Plates — Xon-Lead Plates — 
Commercial, Battery Designs. Chapter 3 — Chaining Methods — Rectifiers— Con- 
verters — Rheostats — Rules for 'Charging. Chapter 4 — Battery Repairs and Main- 
tenance. Chapter 5 — IiKlustrial Ap^jUcation of Storage Batteries — Glossary of 
Storage Battery Terms. 208 pages. Fully illustrated. Price .... $2.00 



ELECTROPLAT^G 



k NEW ELECTROPLATING BOOK. By Kenneth M. Coggeshall. 

This is one of the most complete and practical books on electroplating and allied 
processes that has be^n publishe^l as a text for the student or professional plater. 
It is written in simple language and explains all details of electroplating in a concise 
yet complete manner. It starts at the begimiing and gives an elementary outline 
of electricity and chemistry as relates to plating, then considers shop layout and 
equipment and gives qU the necessary information to do reliable and profitable electro- 
plating in a modfrn commercial manner. Full instructions are given for the prepara- 
tion and finishing of the work and formulae and complete directions are include<l for 
making all kinds of plating solutions, many of these hEf\lng been trade secrets until 
pubUshed in this instruction manual. Any one interested in practical plating and 
metal finishing will find this book a valuable guide and complete manual of the art. 
Cloth. 135 illustrations. IS early 300 pages. Price $8.00 

FACTORY MANAGEMENT, ETC, 

/LODERN MACHINE SHOP CONSTRUCTION, EQUIPMENT AND 

. MANAGEMENT. By O. E, Perrigo, M.E. - 

I The only work published that describes the modem machine shop or manufacturing 

plant from the time the grass is growing on the site intended for it until the finished 

I product is shipped. By a careful study of its thirty-two chapters the practical man 

■ may economically build, efficiently euuip, and successfully manage the modern machine 

' shop or manufacturing establishment. .1 ust the book needed by those contempiating 

I the erection o*f modern shop buildings, the rebuilding and reorganization of old ones, 

or the introduction of modern shop methods, time and cost systems. It is a book 

written aTid illustrated l^y a practical shop man for practical shop men who are too 

! busy to read theories and want fads. It is the most complete all-around book of its 

i kind ever pubhshed. It is a practical book for practical men. from the apprentice in 

I the shop to the president in the office. It minutelyxlescribes and illustrates ttie most 

\ simple and yet the most efficient time and cost system yet devised. Price . $5.00 

I 21 



CATALOGUE OF GOOD, PRACTICAL BOOKS 



FUEL 

COMBUSTIOIT OF COAL AND THE PREVENTION OF SMOKE. By Wm. 

M. Baku. ^ * 

This book has been prepared with special reference to the generation of heat by the 
combustion of the common fuels found in the United States, and deals particularly 
with the conditions necessary to the economic and smokeless combustioh of bituminous 
Goals in Stationary and Locomotive Steam Boilers. 

The presentation of this important subject is systematic and progressive. The ar- 
rangement of the booii is in a series of practical questions to which are appended 
accurate answers, whictf desct-ibe in language, free from technicalities, the several 
processes involved in the furnace combustion of American fuels; it clearly states th(^ 
essential requisites for perfect combustion, and points out the best method* for furnaces 
construction for obtaining the greatest quantity of heat from any given quality of 
coal. Nearly 350 pages, fully illustrated. Price $1.50 

GAS ENGINES AND GAS 

' 

THE GASOLINE ENGINE ON THE FARM?: 1%S OPERATION, REPAIR 
AND USES. ^By Xeno W. Putnam. 

This is a practical treatise on the Gasoline and Kerosene Engine intended for the man 
who wants to know just how to manage his engine and how to*apply it to all kinds of 
farm work to the best advantage. 
This book abounds with hints and helps for thd farm and suggestion'^ for the homo 
^and housewife. There is so much of value in this book tl^at it is impossible to ade- 
quately describe it in sucli small space. Suffice to say that it is the kind of a book 
every farmer will appreciate and every farm home ought to have. Includes selecting 
the most suitable engine for farm work, its most convenient afnd efficient installation, 
with chapters on troubles, their remedies, and how to avoid t^iem. The care and 
management of the farrq« tractor in plowing, harrowing, harvestmg and road grading 
are fully covered; also plain directions are givew for handliftg the tractor on the road. 
Special attention is given to relieving farm life of its drudgery by applying power to 
the disagreeable small tasks which mnst otherwise be done by hand. INIany home- 
made contrivances for cutting wood, supplying kitchen, garden, and barn with water, 
loading, hauling and unloading hay, delivering grain to th^ bins or the feed trough 
are included; also full directions for making the engine milk thtf cows, churn, wash, 
sweep the house and cleanxthe windows, etc. Very fully illustrated with drawings of 
working parts and cuts showing Stationarv, P'ortable and Tractor Engines doing all 
kinds of farm work. All money-making farms utilize power. Learn how to utilizo 
power by reading the pages of this book. Tt is an aid to the result getter, invaluable 
to the up-t/O-date farmer, student, blacksmith, implement i^ealer and, in fact, all who 
can apply practical knowledge of stationarv gasoline engines or gas tractors to advan- 
tage. 530 pages. Nearly a 80 engravings. Price , . , $3.00i 

WHAT IS SAID OF THIS BOOK: 
"Am much pleased with the book and find it to be very complete and up-to-date. 
I will heartily recommend it to students and farmers whom I think would stand in 
need of such a work, as I think it is an excoptionallv good one." — N. S. Gardiner,. 
Prof, in Charge, Clemson Agr. College of S. C; Dept. of Agri. afld Agri. Exp. Station, 
Clemson College, S. C. 

**I feel that Mr. Putnam's book covers the main points which a farmer should know.'*' 
— B. T, tfurdick, Instructor in Agronomy, University of Vermont, Burhngton, Vt., 
*'It will be a valuable addition to our library upon Farm Machinery." — James AJi 
Farra, Inst, in Agri. Engineering, State University of Ky., Lexington, Ky. 

GASOLINE ENGINES : THEIR OPERATION, USE AND CARE. By A. Htaw 

Verrill. 

The simplest, latest and most comprehensive popular work published on Gasoline* 
Engines, describing what the .Gasoline Engine is; its construction and operation; how 
to mstall it ; how to select it ; how to use it and how to remedy troubles encountered . 

22 



B 



CATALOGUE OF GOOD, PRACTICAL BOOKS 

Intended for Ovrners, Operators and Users of Gasoline IMotors of all kinds. This 
work fully .describes and illdr.-,trates the various types of GasoUno Engines iLsed in 
Motor Boats, Motor Vehicles and Stationary Work. The parts, accessories and 
appliances are described, with chapters on ignition, fuel, lubrication, operation and 

, engine troubles. Special attention is given to the care, operation and repair of motors, 
with useful hints and suggestions on emergency mpfJrs and makeshifts. A complete 
glossary of technical terms and an alphabetically arranged table of troubles and their 
symptoms form most valuabJI^e and unique features of this manual. Nearly every 

1 illustration in the book is original, having been made by the author. Every page is 
full of interest and value. A book which you cannot afford to be without. 275 pages. 
152 specially made engravings. Price $2700 

^AS, GASOLmE, AND OIL ENGINES. By Gardker D. Hiscox. 

[ Just issued, 22d revised and enlarged edition. Every user of a gas engine needs this 

book. Simple* instructive, anti right up-to-date. The only complete work on the 

subject. Tells all about the running and management of gas, gasohne and oil engines, 

( as designed and manufactured, in the United States. Explosive motors for stationary 

marine and vehicle power are'^fuUy treated, together with illustrations of their parts 

and tabulated sizes, also their care and running are included. Electric ignition by 

induction coil and-jump spark are fully explained and illustrated, including valuable 

information on the testing for economy and power an^ the erection of power plants. 

The rules and regulations of the J^oard of Fire Underwriters in regard to the installation 

[1 and management of gasoline motors are given in full, suggesting the safe installation 

' of explosive motor power. A list of United States Patents issued on gas, ga^soline, and 

' oil engines and their adjuncts from 1875 to date is included. 640 fvages. 435 ensrav- 

( ings. Folding plates. Price $3.00 

>AS ENGINE CONSTRUCTION, OR HOW TO. BUILD A HALF-HORSE- 
POWER GAS ENGINE. By Parsell and Weed. 

A practical treatise of 300 pages describing the theory and principles of the action of 
Gas Engines of various types and the design and construction of a half-horse-power 
Gas Engine, with illustrations of the work in actual progress, together with the dimen- 
sioned working dr«a-wings, giving clearly the sizes of the various details; for the student, 
the scientific investigator, and the amateur mechanic. This book treats of the subject 
more from the standpoint of pract(v^e than that of theory. The principles of operation 
of Gas Engines are clearly and simply described, and then the actual construction of a 
half-horse-power engine is taken up, step by step, showing in detail the making of the 
Gas Engine. 3d Editjon. 300 pages. Price $3.00 

;I0W TO RUN AND INSTALL GASOLINE ENGU^ES. By C. Von Culin, 

Revised and enlarged edition ^just issued. The object of this little book is to furnish 
a pocket instructor for the beginner, the busy man who uses an engine for pleasure or 
profit, but who does not have the time or inchnation for a technical book, but simply 
to thoroughly imderstaud how to properly operate, install and care for his own engine. 
The index refers to each trouble, remedy, and subject alphabetically. Being a quick 
reference to find the cause, remedy and prevention fc* troubles, and to become an 
expert with his "own engine. Pocket size. Paper binding. Price . . 25 cents 

jHE MODERN GAS TRACTOR. By Victor W. Pag^. 

I A complete treatise describing all tj^pes and sizes of gasoUne, kerosene and oil tractors. 

5 Considers design v^\d construction exhaustively, gives»complete instructions for c^re, 
operation and -repair, outhnes all practical applications on the road and in the field. 
The best and latest work on farm tractors and tractor power plants. A work needed 
by farmers, students, blacksraiths, mechanics, salesmen, implement dealers, designers 
and engineers. 500 pages. ;N early 300 illustrations and folding plates. Price $8.00 

CHEMISTRY OF GAS MANUFACTURE. By H.^I. Royle. 

This book covers points Ukely to arise in the ordinary course of the duties of the 
engineef or ra;\nager of a gas works not large enough to necessitate the employment 
of a separate chemical staff. It treats of the testing of the raw materials employed 
in the manufacture of illuminating coal gas and of the gas produced. The preparation 
of standard solutions is given as well as the chemical ,and phvsical examination of gas 
coal. S^xSM- Cloth, 328 pages.^ 82 illustrations, 1 colored platt?. Price $5.00 

23 



CATALOGUE OF GOOD, PRACTICAL BOOKS 



GEARING AND CAMS 

BEVEL GEAR TABLES. By D. Ag. Engstrom. 

A book that will at once coiUguend itself to mechanics and draftsmen. Does away 
with all the trisonometry and fancy figuring «n bevel gears, and makes it easy for any- 
one to lay them out or make them just right. TJtiere are 36 full-page tables that 
show every necessary dimenuon for all sizes or combinations you're ap,t to need. No 
puzzling, figuring or guessing. Gives placing distance, all the angles (including 
cutting angles), and the correct cutter to use. A copy of this prepares you for any- 
thing m the bevel-gear line. 3d Edition. 66 pages $1.60 

CHANGE GEAR DEVICES. *By Oscar E. Perrigo. 

A practical book for every designer, draftsman, an(J mechanic interested ij:i the inven- 
tion and development of the devices for feed changes on the different macnines requir- 
ing such mechanism. All the necessary information on this subject is taken up, 
analyzed, classified, sifted, and concentrated for the tise of busy men who have not the 
time to go through the masses of irrelevant matter with which such a subject is usu- 
ally encumbered and select such information as will be useful to ^hem. 
It shows just what has been done, how it has been done, when it was done, and who 
did it. It saves time in huitting up patent records and re-inventing old ideas. 88 
pages • $1.60 

DRAFTING OF pAMS. By Louis Rouillion. 

The laying out of cams is a serious problem unless you know how to go at it right. 
This puts you on the right road for practically any kind of cani you are Ukely to run 
up against. 3d Edition 35 cents 

• HYDRAULICS 

HYDRAULIC ENGINEERING. By Gardner D. Hiscox. , 

A treatise on the properties, power, and resources of water for all purposes. Including 
the measurement of streafns, the flow of water in pipes or^conduits; the horse-power 
of falling water, tm-bine and impact water-wheels, wave motors, centrifugal, recipro- 
cating and air-lift pumps. With 300 figures and diagrams and 36 practical tables. 
All who are interested in water-works development will find this book a useful one. 
because it is an entirely practical treatise upon a subject of present importance, and 
cannot fail in having a far-reaching influence, and for this reason fshould have a place 
in the working library of every engineer. Among the subjects treated are: Historical 
Hydrauhcs, Properties of Water, MeasurerSent of the Flow of Streams; Flow 
from Sub-surface Orifices and Nozzles; Flow of Water in Pipes; Siphons of Various 
Kinds: Dams and Great Storage Reservoirs; City and Town Water Supply; Wells 
and Their Reinforcement; Air Lift Methods of Raising Water; Artesian Wells; 
Irrigation of Arid Districts; Water Power; Water Wheels; Pumps and Pumping 
Machinery; Reciprocating Pumps; Hydraulic Power Transmission; Hydraulic 
Mining; Canals; Ditches; Conduits and Pipe Lines; JSIarine Hydfuulics; Tidal and 
Sea Wave Power, etc. 320 pages. Price $4.50 

ICE AND REFRIGERATION 



II 



POCKETBOOK OF REFRIGERATION AND ICE MAKING. By A. J. 
Wallis-Taylor. 

This is one of the latest and most comprehensive reference books published on the 
subject of refrigeration and cola storage. It explains the properties and refrigerating 
effect of the different fluids in use, the management of refrigerating machinery and the 
construction and insulation or cold rooms with their required pipe sui*face for different 
degrees of cold ; freezing mixtures and non-freezing brines, temperatures of cold rooms 
for all kinds of provisions, cold storage charges for all classes of goods, ice making 
and storage of ice, data and memoranda for constant reference by refrigerating engineers, 
with nearly one hundred tables containing valuable references to every fact and con- 
dition required in the installment and operation of a refrigerating plant. New 
edition just pubUshed. Price $2.00 

24 



CATALOGUE OF GOOD, PRACTICAL BOOKS 



INVENTIONS— PATENTS 

NVENTORS' MANUAL, HOW TO MAKE 4 PATENT PAY. 

This is a book designed as a guide t« inventors in perfecting their inventions, taking 
oufe their patents and disposipj^ of them. It is not in any sense a Patent Sohcitor's 
Cii'cular nof a Patent Broker's Advertisement. No advertisements of any description 
appear in the work. It is a book containing a quarter of a century's experience of a 
successful inventor, together with notes based upon the experience of many other 
inventors. 

Among the subjects treated in this work are: H^w to» Invent. How to Secure a 
Good Patent. Value of Good Invention. How to Exhibit an Invention. How to 
Interest Capital. How to Estimate the Value of a Patent. Value of Design Patents. 
Value of Foreign Patents. Value of Small Inventions. Advice on SeUing Patents. 

! Advice on the Formation of Stock Companies. Advice on the Formation of Limited 
Liability Companies. AdvicQ on Disposing of Old Patents. Advice as to Patent 
Attorneys. Advice as to Selling Agents. Forms of Assignments. License and Con- 
tracts. State Laws Concerning Patent Rights. 1900 Census of the United States by 
Counts of Over 16,000 Population. New revised and enlarged edition. 144 pages. 

: lUustrated. Price ^ $1.25 

' ' KNOTS 

KNOTS, SPLICES AND ROPE WORK. By A. Hyatt Verrill. 

This is a practical book giving complete and simple directions for making all the most 
, useful and ornamental knots in common use, with chapters on Splicing, Pointing, 
Seizing, Serving, etc. This book is fully illustrated with one hundred and fifty 
original engravings, which show how each knot, tie or splice is iormed. and its appear* 
ance when finished. * The book will be found of the greatest value to Campers, Yachts- 
men, Travelers, t3oy Scouts, in fact, to anyone having occasion to use or handle rope 
or knots for any piu-pose. The book is thoroughly reliable and practical, and is not 
only a guide, but a teacher. It^is the standard work on the subject. Among the 
contents are: 1. Cordage, Kinds of Rope. Construction of Rope, Parts of Rope 
Cable and Bolt Rope. Strength of Rope, Weight of Rope. 2. Simple Knots and 
Bends. Terms Used in Handling Rope. Seizing Rope. 3. Ties and Hitches. 4. 
Noose, Loops and I^Iooring Knots. 5. Shortenings, Grommets and Salvages. 6. 
Lashings, Seizings and Splices. 7. Fancy Knots and Rope Work. 12S pages. 150 
original engravings. Price . . .^ i^ $1.00 

, LATHE WORK 

LATHE DESIGN, CONSTRUCTION, AND OPERATION, WITH PRACTICAL 
EXAMPLES OF LATHE WORK. By Oscar E. Perrigo. 
A new re\ised edition, and the only complete American work on the subject, written 
by a man who knows not only how wor^v ought to be done, but who also knows how 
to do it. and how to convey this knowledge to others. It is strictly up-to-date in its 
descriptions ^.nd illustrations. Lathe history and the relations of the lathe to manu- 
facturing are given; also a description of the various devices for feeds and thread 
cutting mechanisms from earlj^ efforts in this direction to the present time. Lathe 
design is thoroughly discussed, including back gearing, driving cones, thread-cutting 
gears, and all the essential elements of the modern lathe. The classification of lathes 
is taken ud, giving the essential differences of the several types of lathes including, 
as is usually understood, engine lathes, bench lathes, speed *lathes, forge lathes, gap 
lathes, pulle'/ lathes, forming lathes, multiple-spindiie lathes, rapid-reduction lathes, 
precision lathes, turret lathes, special lathes, electrically -driven lathes, etc. In addi- 
tion to the complete exposition on construction and desisrn. much practical matter on 
lathe installation, care and operation has been incorporated in the enlarged 1915 edi- 
tion. All kinds of lathe attachments for drilling, milling, etc., are described and 
complete instructions are given to enable the novice^machinist to grasp the art of lathe 
operation as weU as the principles involved in design. A number of diJQQCult machining 



25 



CATALOGUE OF GOOD, PRACTICAL BOOKS 

Operations are described at length and illustrated. The new edition has nearly 500 
pages and 350 illustrations. Price t . $3.00 

WHAT IS SAID OF THIS BOOK: 

•*This is a lathe book from beginnini; to end. and is just the kind of a book which one 
delights to consult, — a masterly weatment of the subjtxit in hand." — Engineering News. 
**This work will be of exceptional interest to anyone who is interested in lathe practice, 
as one very seldom sees such a complete treatise on a^subject a^ this is on the lathe." — 
Canadian Machinery. 

LATHE WORK FOR BEGINNERS. By RAf/MOND Francis Yates. 

A simple, straightforward textbook for those desiring to learn the operation of a 
wood-turning or metal-turning lathe. The first ct>apter tells how-to cli^ose a latho 
and all of the standard types on the market are de-scribed. Simple and more advanced 
lathe work is thoroughly covered and the operation of all lathe attachments such a 
millers, grinders, polishers, etc., is described. Th€ treatment starts from the ver; 
bottom and leads the reader through to a point where he will be able to handle th( 
larger commercial machines with very little instruction. Thp last chapter of tho 
book is devoted to things to make on the lathe and includes a model rapid-fire naval 
gun. This is the only book^ published in this country that treats lathe work from 
the standpoint of the amateur mechanic. 162 illifctrations. About z50 pages I'mo. 
Price . . . $2.00 

TURNING and' BORING TAPERS. By Fred H. Colv^n. ^| 

There are two ways to turn tapers; the right way and one other. This treatise has 
to do with the right way; it*tells you hosv to sta#t the work properly, 'now to set the 
lathe, what tools to use and how to use them, and forty §,nd one other httle things 
that you should know. Fourth edition. Price 36 cents 

LIQUID AIR 

LIQUID AIR AND THE LIQUEFACTION OF GASES. By T. O'Conor Slo]^ 

This book gives the history of the theory, discovery, and manufacture of Liquid Air, 
and contains an illustrated description of all the experiments th'at have excited the 
wonder of audiences all fi'ver the country. It shows how liquid air, like water, ia 
carried hundreds of miles and is handled in open buckets. It tells what may be ex- 
pected from it in the near future. 

A book that renders simple one of the most perplexing chemical problems of the 
century. StartUng developments illustrated by actual experiments. 
It is not only a work of scientific interest and authority, but is intended for the general 
reader, being written in a? popular style — easily understood by every one. Third 
edition. Revised and Enlarged. 394 pages. 1920 Edition. Price . . . $8.00 

LOCOMOTIVE ENGINEERING ; 

AIR-BRAKE CATECHISM. By Robert H. Blackall. ^™ 

This book is a standard text book. It covers the Westin«:house Air-Brake Equipment, 
including the No. 5 and the No. 6 E. T. Locomotive Brake Equipment; the K (Quick 
Service) Triple Yalve for Freight Service; and the Cross-Compound Pump. The 
operation of all parts of the apparatus is explained in detail, and a* practical way of 
finding their peculiarities and dofects, with a proper remedy, is j?iven. It contains 
2,000 questions with their answers, which will enalile any railroad Kian to pass any 
examination on the subject of Air Brakes. Endorsed and used by air-brake instruc- 
tors and examiners on nearly every railroad in the United States. 27th Edition. 411 
pages, fully illastrated with co'lored plates and diagrams. Price $2.50 

26 



CATALOGUE OF GOOD, PRACTICAL BOOKS 

■ :* 

COMBUSTION OF COAL AJTD THE PREVENTION OF SMOKE. By Wm. 
M. Barr.* 

This book has been prepared with special reference to the generation of heat bv the 
combustion of the common fuels found in the United States and deals [>articularly 
with the conditions necessary to the ecuoouiic and ^Il^jkeless combustion of bituminous 
coal in Stationary and Locomotive Steam Boilers. 

Presentation of this important subject is systematic and progressive. The ar- 
rangement of the book is in a series of practical questions to which are appended 
accurate answers, which describe in language free from te^rhnicalities the several 
processes involved in the furnace combustion of American fuels; it clearlv states the 
essential requisites for perfect cona|;Ustion, and points out the best methods of furnace 
construction for obtaining the greatest quautity o£ hea^ from any given quality of 
coal. Nearly 350 pages, fully illustrated. Price $1.50 

)IARY OF A ROUND-HOUSE FOREMAN. By T. S. Eeilly. 

This is the greatest book of raifc'oad experiences ever published. Containing a fimd of 
information and suggestions along the line of handling men, organizing, etc., that one 
cannot atford to miss. 176 pages. Price $1.25 

yINK MOTIONS, VALVES AND VALVE SETTING. By Fred H. Colvin, 
] Associate Editor of Americdtn Machinist. 

i 

, A handy book for the engineer or machinist that clears up the mysteries of valve 

setting. Shows the different valve gears in use. how they work,*aiid why. Piston 

and slide valves of <:liir'erent types are illustrated and explained. A bool: that every 

railroad man in the motive power department ought to ha.vc. Contains chapters on 

j Locomotive Link IMotion, Valve ]\iovements, Settiiig SUdc Valves, Analysis by 

t Diagrams, Modern Practice, Shp of Block, Slice Valves, Piston Valves, Setting Piston 

'\ Valves, .Joy-Allen Val>te Gear, "Walschaert Valve Gear, Gooch Valve Gear, Alfree- 

:> Hubbell Valve Gear, etc., etc. Fully illustrated. Price 75 cents 

OCOMOTIVE BOILER CONSTRUCTION. By Frank A. Kleinhans. 

The construction of boiler? in general is treated, and, following this, the locomotive 
, boiler is taken up in th?? order in wtiich its various parts go through the shop. Shows 

all types of boilers used; gives details of construction; practical facts, such as Ufe of 
4 riveting, punches and dies; work done per day, allow^ance for bending and flanging 
■ sheets, and other data. Including the recent Locomotive Boiler Inspection Laws 
^ and Examination Questions with their answers for Government Inspectors. Contains 
,j chapters on Laj'ilig Out Work; Flanging and Forging; Punching; Shearimr; Plate 
\ Planing; General Tables; Finishing Parts; Bending; Irfachinery Parts; Riveting; 
j Boiler Details; Smoke Box Details; Assembhng and Calking; Boiler Shop 
< Machinery, etc., etc. 

^ There isn't a man who has anything to do with boiler work, either new or repair work, 

I who doesn't need this bOok. The manufacturer, superintendent, foreman, and boiler 

i worker — all need it. No matter what the type of boiler, you'll find a mint of informa- 

1 tion that you ivouldn't be without. Over 400 pages, five large folding plates. 

] Price $3.50 



OCOMOTIVE BREAKDOWNS AND THEIR REMEDIES. By Geo. L. 
Fowler. Revised by Wm. W. Wood, Air-Brake Instructor. Just issued. 
Revised pocket edition. 

It is out. of the question to tr^^ and tell you about every subject that is covered in this 
porkei edition of Locomotive Breakdowns. Just imagine all the common troubles 
that an engineer may expect to happen some time, and then add all of the unexpected 
ones, troubles that could occur, but that you have never thought about, and you will 
find that thev are all treated with the very best methods of repair. Walschaert 
Locomotive Valve Gear Troubles, Electric Headhght /Proubles, as well as Questions 
and Answers o*ii the Air Brake are all included. 312 pages. 8th Revised Edition. 
Fully illustrated $1.50 

JOCOMOTIVE CATECHISM. By Robert Grimshaw. 

The revised edition of "Locomotive Catechism," by Robert Grimshaw, is a New Book 
from Cover to Cover. It contains twice as many pages and double the number of 

27 



CATALOGUE OF GOOD, PRACTICAL BOOKS [I 

illustrations of previous editions. Includes the greatest amount of practical informa' 
tion ever published on the construction and management of modern locomotives 
Specially Prepared Chapters on the Walschaert Locomotive Valve Gear, the Air 
Brake Equipment and the Electric Headlight are given. 

It commends itself at once to/^yory Engineer and Fireman, and to all who are going ii 
for examination or promotion . In plain langfiage, with full, complete answers, not onl^ 
all the questions asked by the examining engineer are given, but those which tin 
young and less experienced would ask the veteran, *nd which old hands ask as"* stick- 
ers." It is a veritable Encyclopedia of the Locomotive, is entirely froe from mathe 
matics, easily understood and thoroughly up-to-date. Contains over 4,000 Examina 
tion Questions with their Answers, 825 pages, 437 illustrations and three foldinj 
plates. 2Sth Revised Edition. Price . . .« $2.6C 

APPLICATION OF HIGHLY SUPERHEATED STEAM TO LOCOMOTIVE^ 

By Robert Garbe. • . ♦ , i 

A practical book which cannot be recommended too liighly to those motive-powe 
men who are anxious to maintain the highest eflfldiency in their locomotives. Con 
tains special chapters on Generation of Highly Superheated Steam : Superheated Stean 
and the Two-Cyhnder Simple Engine; Compounding and Superheating; Designs o 
Locomotive Superheaters; Constructive Details of Locomotives Using Highl? 
Superheated Steam. Experimental and Working Results. Illustrated with folding 
plates and tables. Cloth. Price . . . . "^ $3.0( 

PRACTICAL INSTRUCTOR AND REFERENCE BOOK FOR LOCOMOTIVI 
FIREMEN AND ENGINEERS. By Chas. F. Lockhart. 

An entirely new book on the Locomotive. It appeals to every railroad man, as i 
tells him how things are doftt^ and the right way^to do them. Writteiji by a man wh« 
has had years of practical experience in locomotive shops and on the road firing an( 
running. The information given in this book cannot be<oimd in any other simila 
treatise. Eight himdred and fifty-one questions with their answers are included 
which will prove specially helpful to those preparing for jf^xamination. Practica 
information on: The (construction and Operation of Locomotives; Brealvdowns an( 
their Remedies; Air Brakes and Valve Gears. Rules and Signals are handled in i 
thorough manner. As aibook of reference it cajinot be exqolled. The book is divide : 
into six parts, as follows: 1. The Fireman's iSutiC/S. 2. General Description of tl 
Locomotive. 3. Breakdowns and their Remedies. 4. Air Brakes. 5. Extrac 
from Standard Rules. 6. Questions for Examination. The 851 questions have bee 
carefully selected and arranged. These cover the exanv nations required by tl 
diflierent railroads. 368 pages. 88 illustrations. Price ....... $2.0 

PREVENTION OF RAILROAD ACCIDENTS, OR SAFETY IN RAILROADING 

By George Bradshaw. 

This book is a heart-to-heart talk with Railroad Employees, dealing with facts, n( 
theories, and showing the men in the ranks, from every-dsly experiehce, how acciden 
occur and how they may be avoided. The book is illustrated with seventy origins 
photographs and drawings showing the safe and unsafe methods o/ work. No vision 
ary schemes, no ideal pictures. Just plain facts and Practical Suggestions are given 
Every railroad employee who reads the book is a better and safer man to have ii 
railroad service. It gives just the information which will be the means of preventin 
many injuries and deaths. All railroad employees should procure a copy; read i* 
and do your part in preventing accidents. 169 pages. Pocket size. Fully illustrate 
Price * 60 cen* 

TRAIN RULE EXAMINATIONS MADE EASY. By G. E. Collingwood. 

This is the only practical work on train rules in print. Every detail is covered, an« 
puzzling points are explained in simple, comprehensive language, making it a practica 
treatise for the Train Dispatcher, Engineman. Trainman, and all others who have t> 
do with the movements of trains. Contains complete and rehable information of th 
Standard Code of Train Rules for single track. Shows Signals in Colors, as used o 
the different roads. Explains fully the practical application of train orders, giving 
clear and definite understanding of all orders which may be used. ' The meaning an 
necessity for certain rules are explained in such a manner that the student may kno 
beyond a doubt the rights conferred under any orders he may receive or the acti(* 
required by certain rules. As nearly all roads require trainmen to pass regular exam 
nations, a complete set of examination questions, with their answers, are include^ 

28 



CATALOGUE OF GOOD, PRACTICAL BOOKS 

These will enable the student J:o pass the required examinations with credit to himself 
and the roa<l for which he works. 256 pages. Fully illustrated with Train Signals 
in Colors. Price $1.50 

:he walschaert and other modern.radial valve gears for 

, LOCOMOTIVES. By Wm. W. Wood. 

If you would thoroughly understand the Walschaert Valve Gear you should possess a 

copy of this book, as the author takes the plainest form of a steam engine — a stationary 
] engine in the rough, that will only turn its crank in one direction — and from it builds 
I up — with the reader's help — a modem locomotive equipped with the Walschaert 
' Valve Gear, complete. The point§ discussed are clearly illustrated ; two large folding 

plates that show the positions of the valves of both ii^side (^r outside admission type, as 
y well as the links and other parts of the gear when the crank is at nine different points 
^ in its revolution, are especially valuable in making the movement clear. These employ 

sliding carrdboa^d models whiclf are contained in a pocket in the cover. 

The book is divided into five general di\isions, as follows: I. Analysis of the gear. 
2. Designing? and erecting the-»^'ear. 3. Advantages of the gear. 4. Questions and 
answers relating to the Walschaert Valve Gear. 5. Setting valves with the Wal- 
schaert Valve Gea^; the three primary types of locomotive valve motion; modem 
[j radial valve gears other than the Walschaert; the Hobart All-free Valve and Valve 
J Gear, with questions and answers on breakdowns; thf Baker-Pilliod Valve Gear; the 
I Improved Batier-Pilliod Valve Grear, with questions and answers on breakdowns. 
The questions with full ansr*.vers given will be especially valuable to firemen and engi- 
neers in preparing for an examination for promotion. 245 pages. Fourth Revised 
1920 Edition. Price "I . . . $2.50 

VESTINGHOUSE E-T AIR-BRAKE INSTRUCTION POCKET BOOK. By 

^ Wm. W. Wood, Aii--Brake Infetructor. 

- Here is a book for the railroad man, and the man who aims to be one. It is without 
^ doubt the only comi)lete work pubhshed on the Westinghouse E-T Locomotive Brake 
Equipment. Writteij by an Air-Brake Instructor who knows just what is needed. It 
covere the subject thoroughly. Everything about the New Westinghouse Engine and 
Tender Brake Equipment, including the standard No. 5 and the Perfect ^d No. 6 
style of brake, is treated in detail. ^ Written in plain EngKsh and profusely illustrated 
with Colored Platas, which enable lone to trace the flow of pre-ssures throughout the 
entire equipment. The best book ever published on the Air Brake. Equally good for 
the beginner and the advanced engineer. Will pass any one through any examination. 
It informs and enUghte/is you on every point. Indispensable to every engineman and 
trainman. 

Contains examination questions and answers on the E-T equipment. Covering what 
the E-T Brake is. How it should b% operated. What tt5 do when defective. Not a 
question can be asked of the engineman up for promotion, on either the No. 5 or the 
No. 6 E-T equipment, that is not asked and answered in the book. If you want to 
thoroughly understand the E-T equipment get a copy of this book. It co^'ers every 
detail. Makes Air-Brake troubles and examinations easy. Second Revised and 

Enlarged Edition, 1920. Price $2.50 

^ ■*- 

MACHINE-SHOP PRACTICE 



IMERICAN TOOL MAKING AND INTERCHANGEABLE MANUFACTUR- 
] ING. By J.^V/WooDwoRTH. 

A "shoppy" book, containing no theorizing, no problematical or experimental devices, 
there are no badly proportioned and impossible diagrams, no catalogue cuts, but a 
J valuable collection of drawings and descriptions of defaces, the rich fruits of the author's 
1 own experience. In its 500-odd pages the one subject only, Tool Making, and what- 
ij ever relates thereto, is dealt wth. The work strands without a rival. It is a complete 
^ practical tr(^.at4se on the art of American Tool Maldng^and sj'Stem of interchangeable 
manufacturing as carried on to-day in the United States. In it are described and 
illustrated all^pf the different types and classes of small tools, fixtm'es, de^dces, and 
special appliances which are in general use in all machine-manufacturing and metal- 
working establishments where economy, capacity, and interchangeability in the pro- 
duction of machined metal parts are imperative. Th©.science of jig making is exhaus- 
tively discussed, and particular attention is paid to drill jigs, boring, profiling and milling 

29 



CATALOGUE OF GOOD, PRACTICAL BOOKS 

- -^ 

fixtures and oth.-r devices in which the parts to be m?.cliined are located and fastener 
within the contrivances. Ail of the tools, fixtures, and devices ilkHtrated and d- 
scribed have been or are used foe the actual production of work, such as parts of dn 
presses, lathes, patented machinery, typewriters, electrical apparatus, mechanical ap 
pUances, brass goods, composition parts, mould products, sheet metal articles, drop 
forgings, jewelry, watches, medfils, coins, etc. 531 pages. Price .... $4.6( 

MACHINE-SHOP ARITHMETIC. By Colvin*-Cheney. 

This is an arithmetic of the things you have to do with daily. It tells you plainly 
about: how to find areas in figures; how to find surface or volume of balls or spheres 
handy ways for calculating; about compound g'j'arin^r; cutting screw threads on an^ 
lathe; drilUng for taps.v spee^ls of drills; taps, emery wheels, grindstones, millins 
cutters, etc.: ail about the Metric system with conversion tables; properties of metals 
strength of bolts and nuts; decimal equivalent of an inch. All sorts of raacliine-shoi 
figuring and 1,001 other things, any one of whifeh ought to be-' worth more thai 
the price of this book to you, and it saves you the trouble of bothering the boss. 6tl 
edition. 131 pages. Price ,. 75 centi 

MODERN MACHINE-SHOP CONSTRUCTION, EQUIPMENT AND MAW 
AGEMENT. By Oscar ^E. Perrigo. 

The only work published that describes the Moclern Shop or Mariufacturing Plan 
from the time the grass is growing on the site intended for it until the finished produe 
is shipped. Just the book needed by those contemplating the erection of modern shoi 
buildings, the rebuilding and reorganization of old ones, or the introduction of Moden 
Shop Methods, time and cost systems. Jt is a book written and illustrated by a prac 
tical shop man for practical shop men who are too busy to read t'fieories and want facts 
It is the most complete all-^ound book of its kind ever pubhshed. 400 large quartc 
pages. 225 original and specially-made illustfrations. 2d Revised' and Enlargec 
Edition. Price ^ $6.0C 

•'SHOP KINKS." By Robert Grimshaw. 

A book of 400 pages and 222 illustrations, being entirely different from any othei 
book on machine-shop practice. Dei^arting from conventional stylo, the authoi 
avoids universal or comtVion shop usage and llfiiits his work to showing special wayi 
of doing things better, more cheaply and more rapidly than usual. As a result th< 
advanced methods of representative establishments of the world are placed at tht 
disposal of the reader. This book shows the proprietor where large savings are possibi 
and how products may be improved. To the employee it h.olds out suggestions tha 
properlv applied, will hasten his advancement. Iso shop can afiPord to be without i 
It bristles mth valuable^wrinkles and helpful suggestions. It will benefit all, fron 
apprentice to proprietor. Every machinist, ail any age, should study its pages. Fiftt 
edition. Price $8.0C 

THREADS AND THREAD CUTTING. By Colvin *and Stabel. | 

This clears up many of the mysteries of thread-cutting, such as double and tripli 
threads, internal threads, batching threads, use of hobs, etc. Contains a lot of usefu 
hints and several tables. Third edition. Price 35 centi 

EVERYDAY ENGINEERING— THE BEST MECHANICAL MAGAZINE OI^ 
THE MARKET. ONLY TWO DOLLARS A YEAR FOR TWELVE 
NUMBERS. SUBSCRIBE TO-DAY. 

Every practical man needs a magazine which will tell him how to make and do thing 
A monthly magazine devoted to practical mechanics for every-day men. Its aim 
t;0 popularize engineering as a science, teacliing the elements of apphed mechanic 
and electricity .in a straightforward and understandable manner. The magazii 
maintains its own experim^tal laboratory, where the devices described in articl* 
submitted to the Editor are xirst tried out and tested before they ar€ pubhshed. Th 
important innovation places the standard of the pubhshed material very high, an 
it insures accuracy and dependability. 

The magazine is the only one in this country that specializes in practical model builr 
ing. Articles in past issues have given comprehensive designs for many model boat- 
including submarines and chtisers, model steam and gasohne engines, electric motors 
and generators, etc., etc. This feature is a permanent one in the magazine. 

30 



CATALOGUE OF GOOD, PRACTICAL BOOKS 

■ — -- Jt 

Another popular department is tliat devoted to automobiles and airplanes. Care, 

maintenance, and operation receive full and authoritative treatment. Every article 

is vvritten from the practical, every-day man standpoint, rather than from that of the 

professional. 

The magazine entertains while it instructs. It is f». journal of practical, dependable 

information, given in a style that it(»may be readily assimilated and applied by the 

maji vrith Uttle or no techni^l training. The aim is to place before the man who 

leans toward practical mechanics a series of concise, crisp, readable talks on what 

is going on'and how it is done. These articles are profusely illustrated with clear, 

snappy photographs, specially posed to illustrate the subject in the magazine's own 

studio by its own staff of technically-trained illustrators and editors. 

The subscription price of the Magazine is $2.QJ) pej year of twelve nnmbers. 

Sample copy sent on receipt of twenty cents. 

Enter your subscription to tbjs practical magazine with us. 

HE WHOLE FIELD «0F MECHANICAL MOVEMENTS 
COVERED BY MR. HISCOX'S TWO BOOKS 



i 



We publish two books by Gardner D. Hiscox that will keep you fr 077^'* inventing" things 
that have been done before, and suggest ways of doing things that you have not thought of 
before. Many a 7n(jtn spends time and money, pondering over some mechanical problem, 
only to learn, after he has solved the problem, that the same thing has been accomplished 
and put in ^^'ractice by- others long 4>efore. Time and mbney spent in an effort to accom- 
plish what has already been accomplished are time and money LOST. The whole field 
of mechanics, every kno'un mechanical movement, and practically every device is covered 
by these two books. If the thing you want has been invented, it is illustrated in them. If 
it hasn't been invented, then you'll find in them the nearest things to what you want, some 
movements or devices that will apply in your case, perhaps; or which will give you a key 
from which to wolt. No book or set of books ever published is of more real value to tne 
Inventor, Draftsman, or-^ practical Jji^echanic than the two ^•lumes described below. 

Mechanical movements, POV/ERS, and devices. By Gardner d. 
Hiscox. 



- into 

eighteen sections or chapters, in which the subject-matter is classified under the follow- 
ing heads: ^Mechanicals Powers; Transmission of Power; Measurement of Power; 
Steam Power; Air Power Apphances; Electric Power and Construction; Navigation 
and Roads; Gearing; Motion and De\ices: Controlhng Motion: Horological; 
Mining; Mill and Factorj^ Apphances; Construction and Devices; Drafting De\ic6s; 
il Miscellaneous Devices, etc. loth edition enlarged. 400 octavo pages. Price . $4.00 

ikECHANICAL APPLIANCES, MECHANICAL MOVEMENTS AND NOVEL- 
TtIES of CONSTRUCTION. By Gardner D..Hiscox. 

This is a supplementary^ volume to the one upon mechanical movements. Unhke the 
first volume, which is more elementary in character, tiiis volume contains illustrations 
and descriptions of many combinations of motions and of mechanical de\ices and 
apphances fomid in different hues of machinery, each device being shown by a Une 
drawing with a description showing its working parts and the method of operation. 
From the multitude of devices described and illust*'ated might be mentioned, in 
passing, such items as conveyors and elevators, Prony brakes, thermometers, various 
types of boilers, solar engines, oil-fuel bm-ners, condensers, evaporators, Corliss and 
ottier valve g*?,ars, governors, gas engines, water motors of various descriptions, air- 
ships, motors and dynamos, automobile and motor bicycles, railway lock signals, 
car couplers, hnk and gear motions, ball bearings, breech block mechanism for heavy 
guns, and a large accumulation of others of eqiial importance. 1,000 speciaUy made 
engravings. 396 octavo pages. 4th Edition enlarged. Price :$4.00 

31 



CATALOGUE OF QOOD, PRACTICAL BOOKS 

MACHINE-SHOP TOOLS AND SHOP PRACTICE. By W. H. Vandervoort. 

A work of 555 pages and 673 illustrations, describing in every detail the construction, 
operation, and manipulation of both hand and machine tools. Includes chapters 
on filing, fitting, and scraping^ s"arf aces ; on drills, reamers, taps, and dies; the lathe 
and its tools; planers, shapers, and their tc?ols; milling machinas and cutters; gear 
cutters and gear cutting; drilling machines and dirjl woriv; grinding machines and 
their work; hardening and tem])ering; gearing, belting, and transmi.ss|on maichinery; 
useful data and tables. 6th edition. Price $4.50 

COMPLETE PRACTICAjL MACHINIST. By Joshua Rose. 

The new, twentieth revised and enlarged edition }s now ready. This is one of the 
best-known books on machine-shop work, and written for the tsracticttl workman 
in the language of the workshop. It gives full, practical instructions on the use o( 
all kinds of metal-working tools, both hand and <\mchine, and tells how the work 
should be properly done. It covers lathe work, vise work, drills and drilling, taps 
and dies, hardening and tempering, the making and use of tools, tool grinding, mark- 
ing out work, machine tools, etc. No machinist's hbrary is Complete without tliis 

volume. 547 pages, 432 illustrations. 1920. Price $8.00 

•- 

HENLEY'S ENqYCLOPEDIA OF PRACTICAL ENGINEERING AND ALLIED 
TRADES. Edited by Joseph G. Horner, A.M.I.Mech.E. 

This book covers the entire practice of Civil and Mechanical Engineering. The 
best known experts in all branches of engineering have contributed tq these volurao 
The Cyclopedia is admirably well adapted to the needs of the beginner and the soli 
taught practical man, as well as the mechanical engineer/ designer, draftsman, she 
superintendent, foreman and machinist. 

It is a modem treatise in five volumes. Handsomely bouivd in half morocco, eac 
volume containing nearly 500 pages, with thousands of illustrations, including dia 
grammatic and sectional drawings with full explanatory detaife. For the complete 
set of five volumes. Pri^e ,. . . * $30. OC 

MODEL MAKING Including Workshop Practice, Design and Construction o\ 
Models. Edited by Raymond F. Yates. Editor of *^ Everyday Engineering 

Magazine.^ ^ 

». 

This book does not describe the construction of toys. Its'pages are devoted to modo 
engineering and the mechanical sciences associated with it. It contains dcscriptiom 
with illustrations of the complete models made by some of the leading model engineen 
in this country. It is the only book published on this imiSortant subject. 
The first part of the book is devoted to the mechanical sciences and processes relato{ 
to model engineering and mechanics in general. To the inexperienced workman, win 
wishes to make models but is untrained in the fundamental mechanics, tliis book wil 
afford all the information necessary. For the experienced mechanic, there are man; 
hints and short cuts that will be found helpful. Few mechanics, no matter how wei 
trained, know how to make their own patterns. Yet a cornplete treatise on tliis im 
portant craft is given. The same holds true in regard to the inteUigent use of abrasive 
in the home shop. This, too, is completely covered in a way that wiil not only help th 
beginner but teach the trained man a few things that he may not have uhderstoo. 
before. In short, the fore part of the book will prepare men to more thoroughly imdi c 
stand the processes connected with model making no matter what their standing. 
This book will help you to become a better mechanic. Ttis full of surr^restions for the- 
who like to make tilings, amateur and professional alike. It has ben prepared i- 
pecially for men with mecKaniral hobbies. Some may be enorine^s, mnrhinists. je v 
elers, pattern makers, office clerks or bank presidents. IMen from various walks 
life have a peculiar intere<=:t in model engineerinsr. IMonEL Mvktxg will b^ a heln ar 
an inspiration to such men. It tells them "how-to-do" and *' how-to-make" t^'ir^ ' 
in simple, understandable terms. Not onlv this, it is full of good, clrar wo' ;.; . 
drawings and photographs of tlie models and apparatus described. Each mod- 1 V 
been constructed and actually works if it is made according to directions. .375 mcr' 
300 illustrations. Price $3.C' 

32 



CATALOGUE OF GOOD, PRACTICAL BOOKS 

SHOP PRACTICE FOR HOME MECHANICS. By Raymond Francis Yates. 

A thoroughlj- practical and helpful treatment prepared especially for those who have 
had little or no experience in shop work. The introduction is given over to an ele- 
mentary explanation of the fundamentals of nu)ec4janical science. This is followed 
by several chapters on the use of smriill tools and mechanical measuring instruments. 
Elementary and more advanced lathe work is treated in detail and directions given 
for the construction of a number of iLseful shop appUances. Drilling and reaming, 
heat treatniont of tool steel, special lathe operations, pattern miaklng, grinding, and 
grinding operations, home foundry work, etc., make up the rest of the volume. The 
book omits notliing that will be of use to those who use tools or to those who wish 
to learn the use of tools. The"^great number of clear engravings (over 300) add 
tremendously to the text matter and to the value of the 'C'olume as a visual instructor. 

Octavo, about 350 pages. 309 engravings. Price $8.00 

I* 

MARINE ENGINEERING 

THE NAVAL- ARCHITECT'S^ AND SHIPBUILbER'S POCKETBOOK. Of 

Formulae, Rules, and Tables and Marine Engineer's and Surveyor's Handy 
Book of Reference. By Clement Mackrow and Lloyd Woollard. 

The eleventh reviac^d and enlarged edition of this most comprehensive work has just 
been issued. It is al^solutely indispensable to all engaged in the Shipbuilding Industry, 
as it condeLfses into a" compact foi*m all dat a and formifiiiielthat are ordinarily required. 
The book is completely up to dat«, including among other subjects a section on 
Aeronautics. 750 pages, Ump leather binding. Price $6.00 

^MARINE ENGINES AND BOILERS— THEIR DESIGN AND CONSTRUC- 
TION. THE STANpARD BqOK. By Dr. G. Ba^er, Leslie S. Robertson 
and S. Bryan Donkin. 

In the words of Dr. Bauer, the present work owes its origin to an oft felt want of a 
condensed treatise er^i bodying the theoretical and practical rules used in designing 
marine engines i*nd boilers. The need of such a work has been felt by most en- 
gineers engaged in the construction and working of marine engines, not only by the 
younger men, but also by those ot greater experience. The fact that the original 
German work was written by the chief engineer of the famous Vulcan Works, Stettin, 
is in itself a guarantee that this book is in all respects thoroughly up-to-date, and 
that it embodies all the information which is necessary for the design and construction 
of the highest types of marine engines and boilers. It may be said that the motive 
power which Dr. Bauer has placed in the fast Germaij. hners that have been tamed 
out of late yea*s from the Stettin Works represent the very best practice in marine 
engineering of the present day. The work is clearly written, thoroughly systematic, 
theoretically sound; wliile the character of the plans, drawings, tallies, and statistics 
is without reproach. The illustrations are careful reproductions from actual working 
drawings, with some well-executed photographic \dews of completed engines and 
boilers. 744 pages. 550 illustrations, and numerous tables. Cloth. Price. $10.00 

toODERN SUBMARINE CHART. 

A cross-section view, showing clearly and distinctly all the Interior of a Submarine 
of the latest type. You get more mformation from this chart about the construction 
and operation of a submarine than in any other waj.'. No details omitted — every- 
Ifcing IS accurate and to scale. It is absolutely correct in every detail. ha\dng been 
approved by naval en2:ineers. All the marhinery and devices fitted in a modem 
Submarine Baat are shown, and to iTiake the en^ravini^: more readily understood 
all the features are shown in operative form, with Officers and Men in the act of per- 
forming the duties assigned to them in sc'-vice conditions. THIS CHART IS REALLY 
AN ENCYCLOPEDIA OF A SUBMARINE. It ns educational and worth many 
times its cost. Mailed in a tube for 25 cents 

33 



CATALOGUE OF GOOD, PRACTICAL BOOKS 



MANUAL TRAINING 

ECONOMICS OF MANUAL 'TRAINING. By Louis Rouillion. 

The only book published that gives just the information needed by all interested ir 
Manual Training, regarding Buildings, Equipment, and Supplies. Shows exactly 
what is needed for all grades of the work from the Kindergarten to the High and 
Normal School. Gives itemized lists of everything used in Manual Training Work 
and tells just what it ought to cost. Also shows where to buy suppUes, etc. Contains 
174 pages, and is fully illustrated. 2d edition. 'Price $2.00 

MINING • 

PROSPECTOR'S FIELD-BOOK AND GUIDE. ' By H. S. Osborn. 

Ninth edition, revised and enlarged by IM. W. von Bemewitz! The last edition oi 
this volume was published iii^ 1910. It and the previoiLs seven editions were suitable 
for those times. The new ninth (1920) edition will be found suitabll' for tire present 
time. While the old-time prospector will always be ai^ important factor, the knowl- 
edge of and search for the coimnon and rarer nunerals is bringing out men who are 
trained to some^ degree. In the Held they need a handy and suggestive pocket-book 
containing hints on prospecting — where to search and how to test — couched in simple 
terms. The chapter on preUminary instructions covers the fit/idamentals of a study 
of the earth's crast. Theq^ follow discussions on practical mineralogy, crystallog- 
raphy, th© value of the blowpipe in proSi)ectirt^, surveying, and cltpmical tests in 
the field. Separate chapters are given to ttie precious ai^fl base metals, also to the 
non-metallic minerals. The chapter on the non-ferroas or alloy group of minerala 
is entirely new, wlnle the section on oil has been expanded. Surficial indications foe 
copper receive full attention. The chapter on gems has beeiy rewritten and matters 
concerning gemstones used for industrial purposes, such as abrasives, included. A ger 
eral chapter covers manv useful minerals and salts. An important guide and sugge- 
tive aid tliroughout the new book are the ntt;ny brief di scriptions of ore deposit 
of all minerals occurring in scattered parts of the world. No other prospector's boo . 
contains this class of mformation. In the appendi.K will be found numbers of uscfi ■ 
tables, and a complete glossary of mining and mineralogical terms. The ninth editio 
of Osborn's Prospector's Field Book and Guide will ba^ found up to date, wort 
while, and full value for the money asked. Flexible fabriko-id. 375 pages. .' 
illustrations. Price . .f . $3.0^ 

PATTERN MAKING 

f 

PRACTICAL PATTERN ^MAKING. By F. W. Barrows. . 

This book, now in its second edition, is a comprehensive and entirely practical treatise 
on the subject of pattern making, illustrating pattern work in both wood and metal 
and with detinite instructions on the use of plaster of Paris in the trade. It give? 
specific and detailed descriptions of the materials used by pattern makers and de- 
scribes the tools, both thoas for the bench and the more interesting machtae tools 
having complete chapters on the Lathe, the Circular Saw, and the Band Saw. It give? 
many examples of pattern work, each one fully illustrated and explained with mucl 
detail. These examples, in their great variety, offer much that will be found o 
interest to all pattern makers, and especially to the younger ones, who are seeking 
information on the more advanced branches of their trade. 

In this second edition of thQ work will be found much that is new, even to those whi 
have long practised this exacting trade. In the description of patterns as adapted 
to the Moiilding Machine many difficulties which have long prevented the rapid anc 
economical production of castings are overcome; and this great, new branch of th 
trade is given much space. Stripping plate and stool plate work and the less exp " 
sive vibrator, or rapping plate work, are all explained in detail. 
Plain, everyday rules for lessening the cost of patterns, with a complete system cij 
cost keeping, a detailed method of marking, appUcable to all branches of the trade| 

34 



CATALOGUE OF GOOD, PRACTICAL BOOKS 

with complete information showing what the pattern is, its specific title, its cost, 
date of production, material of which it is made, the number of pieces and core- 
boxes, and its location in the pattern safe, all condensed into a most complete card 
record, with cross index. 

The book closes with an original and practical meffij??d for the inventory and valua- 
tion of patterns. Containing ne-irly 311) pages and 170 illustrations. Price . $2.50 

MOTOR BOATS 

r 

OTOR BOATS AND BOAT MOTORS. By Victor wI'Page and A. C. Leitch. 

All who a4"e interested in motof^ boats, either as owners, builders or repairmen wiH 
find this latest work a most comprehensive treatise on the design, construction, opera- 
tion and repair of motor boats and their power plants. It is really two complete 
books in one cover as it consists of two parts, each complete in itself. Part One deals 
with The Hull and Its Fittings, Part Two considers The Power Plant and Its 
AuxiLL^RiES. A valuable feature of this book is the complete set of dimensioned 

, working drawings detailing the construction of five dfc'Terent types of boats ranging 
from a 16-fooii. shallow draft, timnel stem general utihty craft to a 25-foot cabin 
cruiser. These plans are by A. C. Leitch, a practical boat builder and expert naval 

. architect and are complete fn every particular. Full instructions are given for the 
selection of a power plant and its installation in the hull. Valuable ft<l\ice is included 
on boat and engine operation and latest designs of motors are described and illustrated. 
The instructions for 40verhauling boat and engine are worth many times the small 
cost of the book. It is a comprehensive work of reference for all interested in motor 
boating in apy of its phases. Octavo. Cloth. 350 illustrations. 500 pages. 
Price $4.00 

K 

PERFUMERY 



RFUMES AND COSMETICS, THEIR PREPARATION AND MANUFAC- 
TURE. By G. W. AsKiNSON, Peri'umer. 

lA comprehensive treatise, in which there has been nothing omitted that could be of 
value to the perfu<»or or manufacturer of ^oilet preparations. Complete directions 
making handkerchief perfumes, ^ -ilts. sacht-cs, fumigating pastilles; 

irations for the care of the skin, *" . the hair, cosmetics, hair dyes and 

r toilet articles are given, also a de jiption of aromatic substances: their 

:re, tests oi purity, and wholesale i^^.^uJ:'cvjiure, including a chapter on synthetic 
i icts, with formulas fctf- their use. A Look of general, as well as trofessionai in- 
...vst. meeting tne wants not only of the druggist and perfume manufacturer, but 
ilso of the gener d pubhc. Among the contents are: 1. ^he History of Perfumery. 
i. About Aromatic Substances in Gtneral. 3. Cdors from the Vegetable Kingdom. 
t. The Aromatic Vegetable Substances Employed in Perfumery. 5. The Animal Sub- 
^'Ttances Used in Perfumery. 6. The Chemical roducts tJsed in Perfumery. 7. TheEx- 
'fraction of Odors. 8. The Special Characteristics of Aromatic Si:l: stances. 9. TheAdul- 
j.tionof Esseitial OUs ani Their Recognition. 10. Synthetic Products. 11. Table of 
sical Properties of. Aromatic Chemicals. 12. Ihe Es&ences of Extracts En ployed 
r'erfumery. 13^ Directions for Making the Most Important Essences and Extracts. 
,^4. The Divisi3n of Perfunery. 1 ">. The Manufacture of Handkerchief Perfumes. 
^6. Formulas for Handkerchief Perfumes. 17. Ammoniacal and Acid Perfumes. 
.8. Dry Perfumes. 19. Formulas for Drv Perfumes. 20. The Perfumes Used for 
-^fumigation. 21. Antisen tic and Theraneutic Value of Perfumes. 22. Classif cation of 
)dors. 23. Some Soeciil Perfumery Products. 24. Hygiene and Cosmetic Perfumery. 
■5. Preparations for the Care of the Skin. 26. IVfanufacttere of Casein. 27. Formulas 
or Emulsions. 28. Formulas for Cream. 29. Formulas for Meals, Pastes and Vege- 
able Milk, 30. Preparations Us-^d for the Hair. 31. Formulas for Hair Tonics and 
'iestorers. 32. Pomades and Hair Oils. 33. Formulas for the Manufacture of 
'omades and Hair Oils. 34. Hair Dyes and Depilatories. 35. Wax Pomades. Bando 
nes and Brilliantines. 36. Skin Cosmetics and Face lections. 37. Preparations for 
" Xails. 38. Water Softeners and Bath Salts. 39. Preparations for the Care of the 
-ith. 40. The Colors Used in Perftmiery. 41. The Utensils Used in the T<Mlet, 

f 35 



CATALOGUE OF GOOD, PRACTICAL BOOKS 

Fourth edition much enlarged and brought up-t^-date. Nearly 400 pages, illi 
trated. Price • . . $5.( 

WHAT IS SAID OF THIS BOOK: 
*' The most satisfactory wori^ f)n the subject of Perfumery that we have ever seen. 
*' We feel safe in saying that here is a book cju Perfumery that will not disappoint yc 
for it has practical and excellent formulae that are within your abihty to prep£ 
readily. > 

"We recommend the volume as worthy of confidence, and say that no.purchaser will 
disappointed in securing from its pages good value for its cost, and a large divide 
on the same, even if he should use but one per cent of its working formulae. Tht 
is money in it for every user of its informati*jn." — Pharmaceutical Record. 

HENLEY'S TWENTIETH CENTURY BOOK OF RECIPES, FORMULA 
AND PROCESSES. Edited by G. D. Hisc6x. 

The most valuable techno-chemical receipt hoolf pubhshed. Contains over 10,0 
practical receipts, many of which will prove of special value to t 
perfumer. Cloth Bound. Price $4,( 

' PLUMBING 



MECHANICAL DRAWING FOR PLUMBERS. By R. M. Starbuck. 

A concise, comprehensive and practical treatise on the subject of mechanical drawJ 
in its various modern apf>hcations to the wor^ of all who, are in any way connect 
with the plumbing trade. Nothing will so help the plumber in estimating and 
explaining work to customers and workmen as a knowicdge of drawing, and to t 
workman it is of inestimable value if he is to rise above his position to positions 
greater responsibihty. Among the chapters contained are: 1. Value to plumber 
knowledge of drawing ; tools required and their use ; comm5n views needed in mecl 
ical drawing. 2. Perspective versus mechanical drawing in -showing plumbing 
struction. 3. Correcif and incorrect method^ in plumbin>^ drawing ; plan and eleva 
explained. 4. Floor and cellar plans and elevation; scale drawings; use of trian 
5. Use of triangles; drawing of fittings, traps, etc. 6. Drawing plumbing elevat 
and fittings. 7. Instructions in drawing plumbing elevations. 8. The drawir 
plumbing fixtures; scale drawings. 9. Drawings of fixtu^^es and fittings. 10. In 
of drawings. 11. Shading of drawings. 12. Shading of di^-awings. 13. Secti . 
drawings; drawing of ^^reads. 14. Plumbing elevations from architect's plan. 15. h 
vations of separate parts of the plumbing system. 16. Elevations from the architect 
plans. 17. Drawings of detail plumbing connections. 18. Architect's plans and plur 
ing elevations of residence. 19. Plumbing elevations of residence (continued) ; plur 
ing plans for cottage. 20. Plumbing elevations; roof connections. 21. Plans : 
plumbing elevations for six-flat building. 22. Drawing 'of various parts of the plur 
ing system; use of scales. 23. Use of architect's scales. 24. Special features in 
illustrations of country plumbing. 25. Drawing of wrought-iroR piping, valves, raoa 
tors, coils, etc. 26. Drawing of piping to illustrate heating systems. 150 illustratio' 
Price $g 

MODERN PLUMBING ILLUSTRATED. By R. M. Starbuck. 

This book represents the highest standard of plumbing wOrk. .vlt has been adoc 
and used as a reference book by the United States Government, in its sanitary wo 
Cuba, Porto Rico, and the PhiUppines, and by the principal Boards of Health o 
United States and Canada. 

It gives connections, sizes and working data for all flxtiu-es and groups of fixtures, 
is helpful to the master^ plumber in demonstrating to his customers and in fig J, 
work. It gives the mechanic and student quick and easy access to the best jn*.4 
plumbing practice. Suggestions for estimating plumbing construction are contai 
in its pages. This book represents, in a word, the latest and best up-to-date pra4 
and should be in the hands of every architect, sanitary engineer and plumber 
wishes to keep himself up to the minute on this important feature of construct 
Contains following chapters, each illustrated with a full-page plate: Kitchen » 
laundry tubs, vegetable wash sink; lavatories, pantry sinks, contents of marble sj 
bath tub, foot and sitz bath, shower bath; water closets, venting of water closets; 



36 



CATALOGUE OF GOOD, PRACTICAL BOOKS 

down water closets, water cloe^^^ets operated by flush valves, water closet range ; slop sink, 
urinals, the bidet ; hotel and restaurant sink, grease trap: refrigerators, safe wastes, laun- 
dry waste, lini3S of refrigerators, bar sinks, soda fountain sinks; horse stall, frost-proof 
water closets; connections for S traps, venting; connections for drum traps; soil pipe 
connections; supporting of soil pipe; main trap aiKl fresh air inlet; floor drains and 
cellar draiiLs. subsoil drainage; wat^r closets and floor connections; local venting; 
connections for bath rooms; connections for bath rooms, continued; connections for 
bath rooHLS, continued; connections for bath rooms, continued; examples of poor 
practice; roughing work ready for test; testing of plumbing system; method of con- 
tinuous venting; continuous venting for two-floor work; continuous venting for two 
lines of fixtures on three or more floors; continuous venting of water closets; plumb- 
ing for cottage house; construction for cellar piping; plumbing for residence, use of 
special fittings; plumbing for two-flat house; plumbiftig for apartment building, plumb- 

. ing for double apartment building; plumbing for oflQce building; plumbing for pubhc 
toilet rooms; i^lumbing for pufehc toilet rooms, continued; plumbing for bath estab- 
lishment'; plumbing for engine house, factory plumbing; automatic flushing for 
schools, factories, etc.; use of flushing valves; urinals for public toilet rooms; the 
Durham system, the destruction of pipes by electrolysis ; construction of work without 

. use of lead; automatic sewage lift; automatic sump tank* country plumbing; construc- 
tion of cesspools ; peptic tank and automatic sewage siphon ; country plumbing ; water 
supply for coimtry house; thawing of water mains and service by electricity; double 
boilers; hot water supply of large buildinejs; automatfo control of hot water tank; sug- 
gestion for estimating plumbing l^onstruction. 407 octavo pages, fully ifliLstrated by 58 
full-page engravings. Thi^J, revised and enlarged edition just issued. Price . $5.00 

>TANDARD PRACTICAL PLUMBING. By R. M. St.4jibuck. 

A complete practical treatise of 450 pages covering the subject of Modem Plumbing 
in all its branches, a. large amount of space being devoted to a very complete and 

Sractical treatment of the subject of Hot Water Supply and Circulation and Range 
toiler Work. Its thirty chapters include about every phase of the subject one can 
think of, making it an indispensable work to the master plumber, the journeyman 
plumber, and the apprentice plumber, containing chapters on: the plumber's tools; 
wiping solder; comiJosition and use; joint wiping; lead work; traps; siphonage of 
traps; venting; co-ntinuous venting; house sewer and sewer connections; house drain; 
soil piping, roughing; rnain trap and fresh air inlet; floor, yard, cellar drains, rain 
leaders, etc.; fixture Wastes; water closets; ventilation; improved plumbing connec- 
tions; residence plumbing; plumbing for hotels, schools, factories, stables, etc.; 
modem country plumbing; filtration of sewage and water supply; hot and cold 
supply; range boilers^ circulation; circulating pipes; range boiler problems; hot 
water for large buildings; water hft and its use; multiple connections for hot water 
boilers; heating 6f radiation by supply system; theory for the plumber; drawing for 
I the plumber. FuUy illustrated by ai7 engravings. Pric«5 $3.60 

. RECIPE BOOK 

lENLEY'S TWENTIETH CENTURY BOOK OF RECIPES, FORMULAS AND 
PROCESSES. Edited by Gardner D. Hiscox. 

The most valuable Techno-chemical Formula Book published, including over 10,000 
selected scientific, chemical, technological, and practical recipes and processes. 
This is the most complete Book of Formulas ever pubhshed, giving thousands of 
recipes for tht* manufacture of valuable articles for everyday use. Hints, Helps, 
Practical Ideas, and Secret Processes are revealed within its pages. It covers every 
branch of the useful arts and tells thousands of ways of making money, and is just the 
book everyone should have at his command. 

Modem in its treatment of every subject that properly falls within its scope, the book 
may truthfully be said to present the very latest form^alas to be found in the arts and 
industries, and- to retain those processes which long experience has proven worthy of a 
permanent record. To present here even a limited number of the subjects which find 
a place in this ^valuable work would be difficult. Suffice to say that in its pages will 
be found matter of intense interest and immeasurably practical value to the scientific 
amateur and to him who wishes to obtain a knowledge of the many processes used in 
the arts, trades and manufactiu'e. a knowledge which will render* his pursuits more 
instructive and remunerative. Serving as a reference book to the small and large 
manufacturer and supplying intelligent seekers with the information necessary to 

37 



CATALOGUE OF GOOD, PRACTICAL BOOKS 



conduct a process, the work will be found of inestimaliDle worth to the Metallurgist, the 
Photographer, the Perfumer, the Painter, the Manufacturer of Glues, Pastes, Cements, 
and Mucilages, the Compounder of Alloys, the Cook, the Physician, the Druggist, the 
Electrician, the Brewer, the Engineer, the Foundryman, the Machinist, the Potter, the 
Tanner, the Confectioner, the /^J^iropodist, the Manicure, the Manufacturer of Chem- 
ical Novelties and Toilet Preparations, the I\yer, the Electroplater, the Enameler, the 
Engraver, the Provisioner, the Glass Worker, the Goldbeater, the Watchmaker, the 
Jeweler, the Hat Maker, the Ink Manufacturer, the* Optician, the Farmer, the "Dairy- 
man, the Paper Maker, the Wood and Metal Worker, the Chandler and Soap Maker, 
the Veterinary Surgeon, and the .Technologist in general. 

A mine of information, and up-to-date In every respect. A book which will prove of 
value to EVERYONE, .es it covers every branch of the Useful Arts. Every home 
needs this book; every office, every factory, every store, every pubUc and private en- 
terprise — EVERYWHERE — should have a copy. 800 pages. Cloth Bound. 
Price ^ ............ . $4.00 

WHAT IS SAID OF THIS i^OOK: 

**Your Twentieth Century Book of Recipes, Formulas, and Processes duly received. 
I am gla.d to have a copy of it. and if I could not replace it, money couldn't buy it. It 
Is the best thing of the sort } ever saw." (Signed) M. E. Trux, Sparta, Wis. 
"There are few persons who would not be able to IJnd in the book sonse single formula 
that would repay several times the cost of the book.' 'y-Mer chants' Record and Show 
Window. 

••I purchased yhur book * Henley's Twentieth Century Book of Recipes, Formulas and 
Processes' about a year ago and it is worth its weight in gold." — Wm. H. Murray, 
Bennington, Vt. 

"THE BOOK tfORTH THREE HUNDRED - DOLLARS '* 

"On close examination of your 'Twentieth Century Receipt Book,' I find it to be a. 
very valuable and useful book with the very best of practical information obtainable. 
The price of the book, $3.00. is very small in comparison to the benefits which one can 
obtain from it. I consider the book worth fully three hundred dollars to anyone." 
— I>R. A. C. Spetts, New York. 

"ONE OF T^E WORLD'S MOST* USEFUL BOOKS'' 
"Some time ago, I got one of your 'Twentieth Century Books of Formulas' and have 
made my living from it ever since. I am alone since my husband's death with two 
small children to care for and am trying so hard to support ^thom. I have customers 
who take from me Toilet Articles I put up, following directions given in the book, 
and I have found every one of them to be flne." — Mrs. J. H. McMaken, West Toledo, 
Ohio. ^ 

RUBBER 

RUBBER HAND STAMPS AND THE MANIPULATION OF INDIA RUBBER.. 
By T. O'CoNOR Sloane. 

This book gives full details on all points, treating in a concise and simple manner thai 
elements of nearly everything it is necessary to understand for a conmaencement iai 
any branch of the India Rubber Manufacture. The maldng of all kinds of Rubber 
Hand Stamps, Small Articles of India Rubber, U. S. Government Composition, Datin?: 
Hand Stamps, the Manipulation of Sheet Rubber, Toy Balloons, Iildia Rubber Solu- 
tions, Cements, Blackings, Renovating Varnish, and Treatment for India Rubber 
Shoes, etc.; the Hektograph Stamp Inks, and Miscellaneous Notes, with a Short* 
Account of the Discovery, Collection and Manufacture of India Rubber, are set forth 
in a manner designed to be readUy understood, the explanations being plain and simplo. 
Including a chapter on Rubber Tire Maldng and Vulcanizing; also a chapter on the 
uses of rubber in Surgery ai:d Dentistry. Third revised and enlauged edition. 175 
pages. Illustrated $1.26 

HENLEY'S TWENTIETH CENTURY BOOK OF RECIPES, FORMULASI'^ 
AND PROCESSES. Edited by Gardner D. Hiscox. 
Contains upward of 10,000 practical receipts, including among them formulas oni 
artificial rubber. Cloth Bound. Price . . . . , $4.00 



I 



38 



CATALOGUE OF GOOD, PRACTICAL BOOKS 
SAWS 

SAW FILING* AND MANAGEMENT OF SAWS. By Robert Grimshaw. 
A practical hand-book on filing, gumming, swaging, hammering, and the brazing of 
band saws, the speed, worl&, and power to run circular saws, etc. A handy book for 
those whcihave charge of saws, or for those mechanics who do their own filing, as it deals 
with the proper shape and pitches of saw teeth of all kinds and gives many useful hints 
and rules for gumming, setting, and filing, and is a practical aid to those who use saws 
for any purpose. Complete ta^)les of proper shape, pitch, and saw teeth as well as 
sizes and number of teeth of various saws are includes*. Fourth edition, revised and 
enlarged. Illustrated. Price $1.50 

STEAM ENGINEERING 

1 AMERICAN STATIONARY ENGINEERING. By W. E. Crane. 

This book begins at the boiler room and takes xtf the whole power plant. A plain 

talli on evet'y-day work about engines, boilers, and their accessories. It is not intended 

^ to be scientific or mathematical. All formulas are in simple form so that any one 

I understanding plain arithmetic can readily understand any of them. The author 

5 has made this the most practical book in print ; has given the Results of his years of 

experience, and has included about all that has to do with an engine room or a power 

plant. You are hot left to guess at a single point. You are shown clearly what to 

expect imder the various conditions; how to secure 4^he best results; ways of prevent- 

'l ing "shut downs '"and repairs? in short, all that goes to make up the requirements 

j t of a good engineer, c^^able of taking charge of a plant. It's plain enough for practical 

\ ' men and yet of value to those high in the profession. 

a A partial Mst of contents is: The boiler room, cleaning boilers, firing, feeding; pumps, 
1 Inspection and repair; chimneys, sizes and cost; piping; mason work; fomidations; 
testing cement? pile driving; engines, slov/ and high speed; valves; valve setting; 
CorUss engines, setting valves, sirigle and double eccenteic; air pumps and condensers; 
ditferent types of ccmdensers; water needed; lining up; pounds; pins not square in 
. crosshead or crank; engineers' tools; pistons and piston rings; bearing metal; hard- 
ened copper; drip pipes from cy Under jackets; belts, how made, care of; oils; greases; 
testing lubricants;^ rules and tables, including steam tables; areas of segments; 
squares and s^jiiare roots; cubes and cube root; areas and circumferences of circles. 
Notes on: Brick work; explosions; pumDs; pump valves; heaters, economizers; 
safety valves; lap, lead, and clegrrance. Has a comt^iete examination for a license, 
etc., etc. Second edition. 285 pages. Illustrated. Price $2.50 

ENGINE RUNNER'S, CATECHISM. By Robert Grimshaw. 

A practical treatise for the stationary engineer, teUing how to erect, adjust, and run 
the principal steam engines in use in the United Spates. Describing the principal 
features of vaHous special and well-known makes of engines: Temper Cut-oflf, Shipping 
and Receiving Foundations, Erecting and Starting, Valve Setting, Care and Use, 
Emergencies, Erecting and Adjusting Special Engines. 

The questions asked throughout the catechism are plain and to the point, and the 
answers are given in such simple language as to be readily understood by anyone. All 
the instructions given are complete and up-to-date ; §^nd they are written in a popular 
style, withoXit any technicalities or mathematical formuLB. The work is of a handy 
size for the pocket, clearly and well printed, nicely bound, and profusely illustrated. 
To young engineers this catechism will be of great value, especially to those who may 
be preparing to go forward to be examined for certificates of competency; and to 
engineers generally it will be of no little service, as they will find in this volume more 
really practical and useful information than is to be found anywhere else within a like 
compass. 387 pages. Seventh edition. Price , \ $2.00 

HORSE-POWER CHART. 

Shaws the horse-power of any stationary engine without calculation. No matter what 

the cylinder diameter of stroke, the steam press^i*e of cut-off, the revolutions, or 

whether condensing or non-condensing, it's all there. Easy to use, accurate, and 

I saves time cind calculations. Especially useful to engineers and designers. 50 cents 

! 39 



CATALOGUE OF GOOD, PRACTICAL BOOKS 

« ■ 

MODERN STEAM ENGINEERING IN THEORY AND PRACTICE. By 
Gardner D. Hiscox. 

This is a complete and practical work issued for Stationary Engineers and Firemen, 
dealing with the care and management of boilers, engines, pmups, superheated steam, t 
refrigerating msichinery, dynanrbs, motors, elevators, air compressors, and all other! 
branches with which the modem engineer must te famiUar. Nearly 200 questions with » 
their answers on steam and electrical engineering, Ukcly to be asked by the Examin- ' 
ing Board, are included. 

Among the chapters are: Historical: steam and its properties: appliances for the 
generation of steam: types of boilers: chimney and its work; heat economy of the 
feed water; steam pumps and their work; incrustation and its work; steam above 
atmospheric pressure; flo^of steam from nozzles; superheated steam and its work; 
adiabatic expansion of steam; indicator and its work; steam engine proportions; slide 
valve engines and valve motion; Corliss engine and jts valve gear; compound engine 
and its theory; triple and multiple expansion engine; steam turbiae; reftigeration : 
elevators and their management; cost of power; steam engine troubles; electric 
power and electric plants. 487 pages. 405 engravings. 3d Edition. . . . $3.50 

STEAM ENGINE CATECHISM. By Robert Grimshaw. 

This unique volume of 413 pages is not only a catechism on the question and answer 
principle, but it contains fornivllas and worked-out answers for all the Steam problems 
that appertain to the operation and management ofrthe Steam Enginer Illustrations 
of various valves and valve gear with their principles of Q»peration are given. Thirty- 
four Tables that are indispensable to every engineer and fireman that wishes to be 
progressive and i# ambitious to become master of his calling are within its pages. It is 
a most valuable instructor in the service of Steam Engineering. Leading engineers 
have recommended it as a valuable educator for the beginner as wfell as a reference book 
for the engineer. It is thoroughly indexed for every detail. Every essential question 
on the Steam Engine with its answer is contained in this valiiable work. Sixteenth 
edition. Price $2.00 

STEAM ENGINEER'S ARITHMETIC. By Colvin-Chenet. 

A practical pocket-book for the steam engineer. Shows how t<v work the problems of 
the engine room and shows "why." Tells how to figure horsepower of engines afid 
boilers; area of boilers; h^s tables of areas and circumferences; steam tables; has a 
dictionary of engineering terms. Puts you on to All of the litf ie kinks in figuring what- 
ever there is to figure around a power plant. Tells you about the heat unit; absolute 
zero : adiabatic expansion ; duty of engines ; factor of safety ; and a thousand and one 
other things; and everything is plain and simple — not the hardest way to figure, but 
the easiest. Second Edition / .... 76 centi 

STEAM ENGINE TROUBLES. By H. Ha^ikens. 

It is safe to say that no book has ever been published which gives the practical en- 
gineer such valuable and comprehensive information on steam engine design and 
troubles. There are descriptions of cylinders, valves, pistons, frames, pillow blocks 
and other bearings, connecting rods, wrist plates, dashpotr. reachrods. valve gears, 
governors, piping, throttle, and emergency valves, safety stops, flywheels, oilers, j 
etc. If there is any trouble with these parts, the book gives you the reasons and I 
tells how to remedy them. 350 pages. 276 illustrations. Price . \ . . $2.50 

BOILER ROOM CHART. By Geo. L. Fowler. 

A chart — size 14 x 28 inches — showing in isometric perspective the mechanism be- 
longing in a modern boiler room. The various parts are shown broken or removed, 
so that the internal construc^tion is fully illustrated. Each part^ is given a reference 
number, and these, with the corresponding name, are given in a glossary printed 
at the sides. Price 25 cents 

STEAM HEATING AND VENTILATION 

, ■ 

PRACTICAL STEAM, HOT- WATER HEATING AND VENTILATION. By 
A. G. King. 

This book is the standard and latest work published on the subject and has been pre- 
pared for the use of all engaged^in the business of steam, hot-water heating, and ventila- 
tion. It is an original and exnaustive work. Tells how to get heating contracts, how 
to install heating and ventilating apparatus, the best business methods to be used, 

40 



CATALOGUE OF GOOD, PRACTICAL BOOKS 



with "Tricks of the Trade" for shop use. Rules and data for estimating radiation 
and cost and such tables and information as make it an indispensable work for every- 
one interested in steam, hot-water heating, and ventilation. It describes all the principal 
systems of steam, hot- water, vacuum, vapor, and vacuum- vapor heating, together 
with the new accelerated systems of hot-water circulation, including chapters on 
up-to-date methods of ventilation and the fan or bk)wer system of heating and ventila- 
tion. Containing chapters on: i. Introduction. II. Heat. III. Evolution of 
artificial heating apparatus. • IV. Boiler surface and settings. Y. The chimney flue. 
VI. Pipe and fittings. Yll. Valves, various kinds. VIII. Forms of radiating 
surfaces. IX. Locating of radiating siu^faces. X. Estimating radiation. XI. Steam- 
heating apparatus. XII. Exhaust-steam heating. XIII. Hot- water heating. XIV. 
Pressure systems of hot- water w^rk. XV. Hot-water appliances. XVI. Greenhouse 
heating. XVII. Vacuum vapor and vacuum e^hausf heating. XVIII. Miscella- 
neous heating. XIX. Radiator and pipe connections. XX. Ventilation. XXI. 
Mechanical ventilation and hot-blast heating. XXII. Steam apphances. XXIII. 
District heating. XXIV. Pipe and boiler covering. XXV. Temperature regulation 
and heat control. XXVI. Business methods. XXVII. Miscellaneous. XXVIII. 
Rules, tables, and useful infc^rmation. 367 pages. 300 detailed engravings. Second 
Edition — Revised. Price $3.60 

800 PLAIN ANSWERS TO DIRECT QUESTIONS ON STEAM, HOT-WATER, 
VAPOR AND VACUUM KEATING PRACTICE. By Alfred G. King. 

This work, just oflP the press, is arranged in question and answer form ; it is intended as 
a guide and text-book for the younger, inexperienced fitter and a*5 a reference book for 
all fitters. This book teUs "how" and also tells "why." No work of its kind has 
ever been pubhsh'ed. It answers all the questions regarding each method or system 
that would be asked by the steam fitter or heating contractor, and may be used as a 
text or reference book, and for examination questions by Trade Schools or Steam 
Fitters' Associations. Rules, data, tables and descriptive methods are given, to- 
gether with much other detailed information of daily practical use to those engaged in 
or interested in the various methods of heating. Valuable to those preparing for 
examinations. Autiswers every quastion asked relating to modem Steam, Hot-Water, 
Vapor and Vacuum Heating. Among the contents are: The Theorj- and Laws of 
Heat. Methods of Heating. Chimneys and Flues. Boilers for Heating. Boiler 
Trimmings and Set\;ings. Radiation. Steam Heatin'g. Boiler, Radiator and Pipe 
^ Connections for St-eam Heating. Hot Water Heating. The Two-Pipe Gravity 
System of Hot Water Heating. The Circuit System of Hot Water Heating. The 
Overhead System of Hot Water Heatins:. Boiler, Radiator and Pipe Connections for 
Gravity Systems of Hot Water Heating. Accelerat-ed Hot Water Heating. Ex- 
pansion Tank Connections. Domestic Hot Water Heating. Valves and Air Valves. 
Vacuum Vapor and Vacuo- Vapor Heating. MechaniogJ Systems of Vacuum Heating. 
Non-Mechanical Vacuum Systems. Vapor Systems. Atmospheric and Modulating 
Systems. Heating Greenhouses. Information, Rules and Tables. 200 pages, 127 
illustrations. Octavo. Cloth. Price $2.00 

STEEL 

STEEL: ITS SELECTION, ANNEALING, HARDENING, AND TEMPERING. 
By E. R. Maiikham. 

This work was formerly known as "The American Steel Worker," but on the pub- 
hcation of the new, revised edition, the pubUshers deemed it advisable to change its 
title to a more suitable one. It is the standard work on Hardening, Tempering, 
and Annealing Steel of all kinds. 

This book tells how to select, and how to work, temper, harden, and anneal steel for 
ever^'thing on earth. It doesn't tell how to temper one class of tools and then leave 
the treatment of another kind of tool to your imagination and judgment, but it gives 
careful instructions for every detail of every tool, whether it be a tap. a reamer or just 
a screw-dris er. It tells about the tempering of small watch springs, the hardening of 
cutler>^ and the annealing of dies. In fact, there isn't a thing that a steel worker 
would want to know that isn't included. It is the standard book on selecting, harden- 
ing, and tempering all grades of steel. Among the chapter headings might be mentioned 
the following subjects: Introduction; the workman; steel; methods of heating; 



41 



CATALOGUE OF GOOD, PRACTICAL BOOKS 

heating? tool steel; forging; annealing; hardening batl^; baths for hardening; harden- 
ing steel; drawing the temper after hardening; examples of hardening ; 'pack harden* 
ing; case hardening; spring tempering; making tools of machine steel; special steels; 
steel for various tools ; causes of trouble ; high speed steels, etc. 400 pages. VerVi i 
fully illustrated. Fourth Edition. Price $8.0a| 

HARDENING, TEMPERING, ANNEALIN*G, A^D FORGING OF STEEL. 
By J. V. Wood WORTH. 

A new work treating in a clear, concise manner all modern processes for the heating, 
annealing, forging, welding, hardening, and tempering of steel, making it a book of 
great practical value to the metal-working niechartic in general, with special directions 
for the successful hardeninii and* tempering of all steel tools used in the arts, including 
milling cutters, taps, thread dies, reamers, both solid and shell, hollow mills, punches 
and dies, and all kinds of sheet metal working tools, sticar blade-s, saws* fine cMtlery, and 
metal cutting tools of all description, as well as for all implements of steel both large 
and small. In this work the simplest and most satisfactory hardening and temper- 
ing processes are given. • 

The nses to which the leading brands of steel may be adapted are concisely presented, 
and their treatment for working under different conditions explafued, also the special 
methods for the hardening an4 tempering of special brands. 

A chapter devoted to the different processes for casr-hardening is also included, and 
special reference made to the adaptation of machinery st«el for tools of various kinds. 
Fifth Edition. 322 pages. 215 illustrations. Price $3.00 

TRACTORS 



THE MODERN GAS TRACTOR. By Major Victor W. Pag6. 

A complete treatise describing all types and sizes of gasoline, kercsene. and oil tractors. 
Considers design and construction exhaustively, givi^s complete instructions for care, 
operation and repair, outlines all practical ai^plications on the road and in the field. 
The best and latest work ow farm tractors and tri^vt or power'»:)lants. A work needed , 
by farmers, students, bUicksmiths, mechanics, saksmen, implement dealers, designers,! 
and engineers. 500 pages. Nearly 300 illustrations and folding plates. Price $3.00j 

TURBINES 



MARINE STEAM TURBINES. By Dr. G. Bauer and O. Lasche. Assist-d 
by E. LuDWiG and H. Vogel. Translated from the German and edited by 
M. G. S. Swallow. 

The book is essentially practical and discusses turbines in wliich the full expansion of 
steam passes tlirough a nmnber of separate turbines arranged for driving two or more 
shafts, as in the Parsons system, and turbines in wliich the complete expansion of 
steam from inlet to exhaust pressure occurs in a turbine on one shaft, as in the case 
of the Curtis macliines. It will enable a designer to carry out all the ordinary calcula- 
tion necessary for the construction of steam tiu*bines, hence it fills .a want which 
is hardly met by larger and more theoreticiil works. Niunerous tables, curves and 
diagrams will be found, which explain with remarkable lucidity the reason why 
turbine blades are designed as they are, the course which steam takes through tur- 
bines of various types, the thermodynamics of steam turbine calculation, the influence 
of vacuum on steam consumption of steam turbines, etc. In a word, the very in- 
formation wliich a designer and builder of steam tm-bines most requires. Large 
octavo, 214 pages. Fully illustrated and containing 18 tables, including an entropy 
chart. Price, net $4.00 



42 






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